On both Orville and H8000 there is a socketed PAL (U106 – just left of EPROM) which can cause much trouble if the socket contacts are bad or corroded, which can easily be the case with a 20 year old unit. When we repair them, we remove the socket and solder the PAL direct to the PCB. This requires some skill. If you don't wish to to that, try "wiggling" it in its socket to polish the contacts.
The unit crashing after startup can of course be many things, but try a new battery (optional), followed by a full init ('8' key held down at first startup screen) Make sure there is no card in the slot.
The NVRAM is U206, a 32 pin chip just below the left expansion connector.