Sound very much like a RAM failure, Agnus socket problem and/or bad contacts. What happens if you try to boot w/o the SupraRAM?
The 00C034F8 address indicates that the system failed while running code in Ranger memory (i.e. SupraRAM memory, you've got an old OCS Agnus or the expansion RAM is not remapped correctly).
If the system also fails w/o the ram expansion, it's most probably the Agnus socket. If it doesn't, inspect the expansion card for any visible damage, esp. around the battery (it hasn't leaked yet??). Switch it off (!) and boot the system. Use a memory test utility to test RAM C00000-C7FFFF.
PS: As it seems the Supra can't be turned off by jumper/switch. You'll need to cut the _EXRAM solder pad on the mainboard to deactivate it.
PPS: Looks like the Supra uses a non-rechargeable battery which doesn't leak. Surely needs replacement anyway.
