We also operate a C525, and it happened a couple of times to us. Once we warmed up the engines applying hot air into the inlet. After 5 min on each engine, the "FAIL" on the ITT scale dissapeared. Another time we tried to start the engine with the ITT Fail indication, with the intention to abort the start if the indication wouldnt become normal (we go to Throtles iddle at 8-10% N2). The moment we pushed Start, the indication became normal.
I am not sure what the MEL says, but for sure one can not fly without ITT Temp Indication, but IMHO to try to start the engines can not do any harm.
Kind regards,