My Serial number is RF3004210001B9 and the market was not working either.
Used the adb logcat and found
E/CheckinTask( 6386): java.io.IOException: Rejected response from server: HTTP/1.1 400 invalid hardware identifier: "RF3004210001B9" is not a valid IMEI (expect 15 decimal digits)
I did as you suggested I edited the file /system/serial_number to FF3004210001B9 rebooted the PE. I used androotfile from the amazon market change the perms on the folder so that I could edit the file in es file explorer.
I had all ready used logged in to youtube and had the data synced. I tried the marked and it just worked.
Thank you for your great work on this pablob.