Sorry to make a new thread. I saw a couple other threads similar to my problem but not exactly the same. So I'm hoping someone can help me out because my N900 is my only phone.

First I made a full backup.
Then used the flasher3.5 to flash to the official PR1.2 for North America
rebooted, SIM not recognized, restored the backup, rebooted, SIM still not recognized
read in another thread to try the Global PR1.2.
flashed the global version, restored the backup, reboot, SIM still not recognized

What should I try next?

Try to downgrade it and see if it works

OK I'm an idiot. i downloaded and flashed the wrong file. i downloaded "RX-51_2009SE_1.2009.42-11.002_PR_COMBINED_002_ARM.bin" because it was at the top of the download page and i saw 1.2 in the name.

what i needed was "RX-51_2009SE_10.2010.19-1.002_PR_COMBINED_002_ARM.bin" which was farther down the download page. flashed and worked perfectly.

sorry for making this thread, a mod can delete this