NOt familiar with whatever version of control you have on a Nardini but I'm familiar with the gremlins of a Fanuc 5T lathe.
Fanuc was really chintzy with my lathe. They used cheap, lame a$$ tin coated connectors and pins on everything as opposed to Mil spec "gold" plated ones which don't corrode. Result: the normal atmospherics, especially those in plant, corrode the cheap tin terminals. Since you're dealing with micro amps (TTL/low voltage signals), it don't take much for a corroded connector to NOT conduct, especially after a period of inactivity that would allow the connector to remain vibration free - vibration might keep the joint sound enough to work but, without it, rigormortis induced electronic gremlins. You can't see electrons, therefore you can't trust them.
When our machine all of a sudden won't come up, we spend the day cleaning/tightening connectors. It comes up pretty near all the time after that. Wev'e even taken to regularly doing it when we're doing P/M on the machine.
If you have a BTR and it is NOT opto isonlated, you could have had a power surge that took out the board due to a ground loop thru the PC and into the Fanuc M/B. That little episode cost me well over $2k to learn and nearly as much again when parts got reassembled wrong (reversed 50 pin connector) after the reassembly process.
Yes, it will work BUT all it takes is the errant situation where a surge sends a ground loop thru the PC into the M/B on the Fanuc. We ultimately found a 13V difference between "ground" between the PC negative on LPT port and the "ground" on the Fanuc. SInce TTL chips will tolerate 5.6vdc max, we toased the SOB's big time.
Depending on the model, Glenn Rowe at Billor Ent (888-424-5567) in Texas can service them and he's much more reasonable than Fanuc. He even bench evaluates them. If they work there, the issue is in the cabinet and that isn't always fun to deal with.
Why? depending on machine maker, they don't always document all the connections. An undocumented ground that shouldn't have mattered, did and kept me from restarting the machine for darn near 2 weeks of chasing everything down. Only a SWAG redundant tying of grounds together (overkill I learned someplace) solved the problem.
If Fanuc used true Mil spec interconnects, this wouldn't happen. But they use(d) lame a$$ "amp" style connectors like you'd use for the power plugs on a PC's HD. REAL expensive call girl only she wears K-mart panties.
I'd guess that (hint) if the PC that got fried by the lightning was attached to the Fanuc and had the grounds NOT optically isolated as mine were not, it is quite possible that your insurance people might get to know the folks from Fanuc and/or Mr. Rowe.
P/M me for the address to send my service fee - no matter what it is, its gonna be cheaper than Fanuc - and I won't bill you for dinner, either. 8-))
Some refurbs are factory warrantied pieces - brand new but infant mortality for some reason or even return unused but can't be sold for new. Look at the warranty and judge accordingly. If it is a factory piece, the refurb should be OK - aftermarket refurb, depends on who did it... A guarantee from an outfit the goes/went bust is pretty much usesless.