I have a Cricket/Audiovox 8910 that powers up only to blank screens
(inner and outer) and does nothing else. Tried leaving battery off for
hours. Checked/reseated all connectors inside. No joy.

Attempts to connect with usb cable and Curitel drivers under winXP
give only an "unknown usb device" despite repeated working on drivers.

What is the hardware reset procedure so I can (if needed) hard-reset &
reflash?

Failing that, can I reflash by jtag? Anyone got the wiring diagram for
the jtag cable, and/or know what software and procedure to use (I
can probably get the s/w & procedure by search, but I had no joy on
cable diagrams and will not pay for such things)?

Failure may have resulted from dropping the phone - I read somewhere
that some of the chips may have crappy soldering from the factory -
any opinions/anecdotes? Or can you tell me which chips? I have a
(last-ditch, crude) method for fixing busted SMT solder.