3GS @4.2.1 inexplicably crashed. Now Unknown IMEI & ICCID

I successfully upgraded my 3GS (AT&T, old bootrom, 5.13.04, Pwnagtool, ultrasn0w) a couple of weeks ago. Today, while listening to a podcast while running a GPS app, the phone inexplicably crashed. COMPLETELY. Now I get a USB icon with a "Restore Needed" message and the "i" button on the lower right of the screen reports:IMEI unknown, ICCID unknown. I doubt I'll ever figure out why this happened but what do I do to restore it? 1) Do I merely option+Restore in iTunes (and select the custom 4.2.1 IPSW I built a couple of weeks ago or 2) should I go through a complete Pwnagtool build, Pwnag DFU mode and reinstall the whole system from backup?

Thanks in advance,
John

OK I got antsy waiting for a response so I:
Rebuilt a custom IPSW using PwnagTool 4.2.
Entered DFU mode (iTunes detected the phone in recovery mode)
Option+Restore in iTunes with Tinyumbrella's TSS server running
ITunes installed and verified iPhone software
iTunes restores iPhone FW
iTunes reports: "iPhone restored and will reboot"
I get an Apple logo on the iPhone display with a task bar that fills about 1/2 way before the screen goes blank
The iPhone then returns to the USB logo (Restore Needed) and iTunes reports "Waiting for iPhone" and iTUnes reports that no SIM is installed when in fact the original AT&T SIM IS installed

I'm Stuck! WHAT HAPPENED?!
What should I try next?

My apology for these two posts. Feel free to delete them. I finally figured this out by searching for 1002 (instead of the other parameters I used), which is the error I get. I have read numerous posts about this since it is now apparent that I have an out of warranty brick. My next question is about advice on purchasing a new phone. My preference is for a factory unlocked iPhone 4 (32GB) but the $650 is a little steep. I will search the posts to see whether a new AT&T iPhone 4 can sustain jailbreaking and unlocking.