Reversibility is always appreciated.
what if any thing goes wrong and you are able to start from begining...!!
well, we can do that at least with N900.
STEP 1.
To start with, we will download the Latest Official Maemo Development Environment from LINK
One can download .exe,deb or other package depending on need and availibility.
This will give you an environment or tool to burn/flash new OS on N900.
on lucid install as
#dpkg -i --force-architecture maemo_flasher-3.5_2.5.2.2_i386.deb
STEP 2.
download PR_COMBINED_MR0_ARM.bin and VANILLA_PR_EMMC_MR0_ARM.bin depending on availibility and requirement from HERE after entering the IMEI number of ur N900.
STEP 3.
Now switch off N900 and holding the U key, connect the device to your computer via USB. Wait until you see a dim screen on your N900 with a Nokia logo in the middle of your screen with an USB icon in the top right corner .
Your are connected in flashing mode. Do not at any point disconnect the cable or restart untill step 4 completed.
STEP 4.
After downloading one can flash the device as following
# flasher-3.5 -F RX-51_2009SE_10.2010.19-1.203.1_PR_COMBINED_203_ARM.bin -f
# flasher-3.5 -F RX-51_2009SE_10.2010.13-2.VANILLA_PR_EMMC_MR0_ARM.bin -f --enable-rd-mode -R
This will flash and reboot after flashing the eMMC contents.
and no guess....u r done.
some intermediate outputs
#flasher-3.5 -F RX-51_2009SE_10.2010.19-1.203.1_PR_COMBINED_203_ARM.bin -f
[sudo] password for nandan:
flasher v2.5.2 (Oct 21 2009)
SW version in image: RX-51_2009SE_10.2010.19-1.203.1_PR_203
Image 'kernel', size 1705 kB
Version 2.6.28-20101501+0m5
Image 'rootfs', size 173696 kB
Version RX-51_2009SE_10.2010.19-1.203.1_PR_203
Image 'cmt-2nd', size 81408 bytes
Version BB5_09.36
Image 'cmt-algo', size 519808 bytes
Version BB5_09.36
Image 'cmt-mcusw', size 5826 kB
Version rx51_ICPR82_10w08
Image '2nd', size 14720 bytes
Valid for RX-51: 2217, 2218, 2219, 2220, 2120
Version 1.4.14.8+0m5
Image 'xloader', size 14848 bytes
Valid for RX-51: 2217, 2218, 2219, 2220, 2120
Version 1.4.14.8+0m5
Image 'secondary', size 109440 bytes
Valid for RX-51: 2217, 2218, 2219, 2220, 2120
Version 1.4.14.8+0m5
Image '2nd', size 14720 bytes
Valid for RX-51: 2101, 2102, 2103
Version 1.4.14.8+0m5
Image 'xloader', size 14848 bytes
Valid for RX-51: 2101, 2102, 2103
Version 1.4.14.8+0m5
Image 'secondary', size 109440 bytes
Valid for RX-51: 2101, 2102, 2103
Version 1.4.14.8+0m5
Image '2nd', size 14848 bytes
Valid for RX-51: 2307, 2308, 2309, 2310
Version 1.4.14.8+0m5
Image 'xloader', size 14848 bytes
Valid for RX-51: 2307, 2308, 2309, 2310
Version 1.4.14.8+0m5
Image 'secondary', size 109440 bytes
Valid for RX-51: 2307, 2308, 2309, 2310
Version 1.4.14.8+0m5
Image '2nd', size 14848 bytes
Valid for RX-51: 2407, 2408, 2409, 2410
Version 1.4.14.8+0m5
Image 'xloader', size 14848 bytes
Valid for RX-51: 2407, 2408, 2409, 2410
Version 1.4.14.8+0m5
Image 'secondary', size 109440 bytes
Valid for RX-51: 2407, 2408, 2409, 2410
Version 1.4.14.8+0m5
Image '2nd', size 14848 bytes
Valid for RX-51: 2301, 2302, 2303, 2304, 2305, 2306
Version 1.4.14.8+0m5
Image 'xloader', size 14848 bytes
Valid for RX-51: 2301, 2302, 2303, 2304, 2305, 2306
Version 1.4.14.8+0m5
Image 'secondary', size 109440 bytes
Valid for RX-51: 2301, 2302, 2303, 2304, 2305, 2306
Version 1.4.14.8+0m5
Image '2nd', size 14848 bytes
Valid for RX-51: 2401, 2402, 2403, 2404, 2405, 2406
Version 1.4.14.8+0m5
Image 'xloader', size 14848 bytes
Valid for RX-51: 2401, 2402, 2403, 2404, 2405, 2406
Version 1.4.14.8+0m5
Image 'secondary', size 109440 bytes
Valid for RX-51: 2401, 2402, 2403, 2404, 2405, 2406
Version 1.4.14.8+0m5
Image '2nd', size 14720 bytes
Valid for RX-51: 2104, 2105, 2106, 2107, 2108, 2109, 2110, 2111, 2112, 2113, 2114, 2115, 2116, 2117, 2118, 2119
Version 1.4.14.8+0m5
Image 'xloader', size 14848 bytes
Valid for RX-51: 2104, 2105, 2106, 2107, 2108, 2109, 2110, 2111, 2112, 2113, 2114, 2115, 2116, 2117, 2118, 2119
Version 1.4.14.8+0m5
Image 'secondary', size 109440 bytes
Valid for RX-51: 2104, 2105, 2106, 2107, 2108, 2109, 2110, 2111, 2112, 2113, 2114, 2115, 2116, 2117, 2118, 2119
Version 1.4.14.8+0m5
Image '2nd', size 14848 bytes
Valid for RX-51: 2501, 2502, 2503, 2504, 2505, 2506
Version 1.4.14.8+0m5
Image 'xloader', size 14848 bytes
Valid for RX-51: 2501, 2502, 2503, 2504, 2505, 2506
Version 1.4.14.8+0m5
Image 'secondary', size 109440 bytes
Valid for RX-51: 2501, 2502, 2503, 2504, 2505, 2506
Version 1.4.14.8+0m5
Image '2nd', size 14848 bytes
Valid for RX-51: 2607, 2608, 2609, 2610
Version 1.4.14.8+0m5
Image 'xloader', size 14848 bytes
Valid for RX-51: 2607, 2608, 2609, 2610
Version 1.4.14.8+0m5
Image 'secondary', size 109440 bytes
Valid for RX-51: 2607, 2608, 2609, 2610
Version 1.4.14.8+0m5
Image '2nd', size 14848 bytes
Valid for RX-51: 2507, 2508, 2509, 2510
Version 1.4.14.8+0m5
Image 'xloader', size 14848 bytes
Valid for RX-51: 2507, 2508, 2509, 2510
Version 1.4.14.8+0m5
Image 'secondary', size 109440 bytes
Valid for RX-51: 2507, 2508, 2509, 2510
Version 1.4.14.8+0m5
Image '2nd', size 14720 bytes
Valid for RX-51: 2201, 2202, 2203, 2204, 2205, 2206, 2207, 2208, 2209, 2210, 2211, 2212, 2213, 2214, 2215, 2216
Version 1.4.14.8+0m5
Image 'xloader', size 14848 bytes
Valid for RX-51: 2201, 2202, 2203, 2204, 2205, 2206, 2207, 2208, 2209, 2210, 2211, 2212, 2213, 2214, 2215, 2216
Version 1.4.14.8+0m5
Image 'secondary', size 109440 bytes
Valid for RX-51: 2201, 2202, 2203, 2204, 2205, 2206, 2207, 2208, 2209, 2210, 2211, 2212, 2213, 2214, 2215, 2216
Version 1.4.14.8+0m5
Image '2nd', size 14848 bytes
Valid for RX-51: 2601, 2602, 2603, 2604, 2605, 2606
Version 1.4.14.8+0m5
Image 'xloader', size 14848 bytes
Valid for RX-51: 2601, 2602, 2603, 2604, 2605, 2606
Version 1.4.14.8+0m5
Image 'secondary', size 109440 bytes
Valid for RX-51: 2601, 2602, 2603, 2604, 2605, 2606
Version 1.4.14.8+0m5
USB device found found at bus 001, device address 009.
Found device RX-51, hardware revision 2101
NOLO version 1.4.14
Version of 'sw-release': RX-51_2009SE_10.2010.19-1.002_PR_002
Sending xloader image (14 kB)...
100% (14 of 14 kB, avg. 966 kB/s)
Sending secondary image (106 kB)...
100% (106 of 106 kB, avg. 13359 kB/s)
Flashing bootloader... done.
Sending cmt-2nd image (79 kB)...
100% (79 of 79 kB, avg. 4676 kB/s)
Sending cmt-algo image (507 kB)...
100% (507 of 507 kB, avg. 20305 kB/s)
Sending cmt-mcusw image (5826 kB)...
100% (5826 of 5826 kB, avg. 13363 kB/s)
Flashing cmt-mcusw... done.
Sending kernel image (1705 kB)...
100% (1705 of 1705 kB, avg. 17223 kB/s)
Flashing kernel... done.
Sending and flashing rootfs image (173696 kB)...
100% (173696 of 173696 kB, avg. 13522 kB/s)
Finishing flashing... done
CMT flashed successfully
$ flasher-3.5 -F R
Resolution RX-51_2009SE_10.2010.19-1.203.1_PR_COMBINED_203_ARM.bin
RX-51_2009SE_10.2010.13-2.VANILLA_PR_EMMC_MR0_ARM.bin
# flasher-3.5 -F RX-51_2009SE_10.2010.13-2.VANILLA_PR_EMMC_MR0_ARM.bin -f -R
[sudo] password for nandan:
flasher v2.5.2 (Oct 21 2009)
Image 'mmc', size 255947 kB
Version RX-51_2009SE_10.2010.13-2.VANILLA
USB device found found at bus 001, device address 009.
Found device RX-51, hardware revision 2101
NOLO version 1.4.14
Version of 'sw-release': RX-51_2009SE_10.2010.19-1.203.1_PR_203
Booting device into flash mode.
Suitable USB device not found, waiting.
USB device found found at bus 001, device address 011.
Raw data transfer EP found at EP2.
Image(s) flashed successfully in 26.549 s (9640 kB/s)!