After flash by some firmware and reboot, my M902 no response and I get below message in TTL...
What can I do now? Thanks.
BootROM - 2.03
Starting CP-0 IOROM 1.07
Booting from SPI NOR flash 1 (0x32)
Error: no valid header till end of media
Error: Failed boot attempt 01. error = 0x041
BootROM - 2.03
Starting CP-0 IOROM 1.07
Booting from SPI NOR flash 1 (0x32)
Error: no valid header till end of media
Error: Failed boot attempt 02. error = 0x018
BootROM - 2.03
Starting CP-0 IOROM 1.07
Booting from SPI NOR flash 1 (0x32)
Error: no valid header till end of media
Error: Failed boot attempt 03. error = 0x018
BootROM - 2.03
Starting CP-0 IOROM 1.07
Booting from SPI NOR flash 1 (0x32)
Error: no valid header till end of media
Error: Failed boot attempt 04. error = 0x018
There isn't much info on the device information page, but reading between the lines, it seems that you start with an SD card installation and then use a sysupgrade image from there.
What specific image did you download and what sequence of events got you to your current state?
While I cannot say with certainty, it seems that you may have damaged your bootloader by trying to flash the SD card image to the device directly. As I said above, I think the SD card image was to supposed to be written to a card... insert the card, boot the device, and then use the sysupgrade image to write to the internal storage.
I could be wrong about the specifics of the upgrade process, but your boot log does seem to confirm that the bootloader is not working properly anymore. You will probably need to find a copy of the bootloader itself (possibly part of the stock firmware image??) along with documentation about how to recover the device from this state. With any luck, someone on these forums may have experience with your router... but I'd start searching the internet (specifically the manufacturer's website (support site/forums), among other places).
Write the image to a SD card then try to boot the card.
Note that the SD images on the server are compressed with gzip (.gz extension) so they have to be uncompressed before writing to the card. The Linux command below will do both in one step by piping the output of gzip to the input of dd.