Sounds interesting. smile

Do you have the manual?

Added 45 minutes later:-

I've had a quick look at that manual, and doubt it will help you much. frown

It sounds like you need to try a valid Micro-SD card in there. I don't suppose you have another MX-400/450/500/550 close at hand?

I'm also wondering how the card became corrupted. think

But "what's on there"? System configuration settings, I should imagine. I'm wondering if you can re-instate these (maybe using a fresh Micro-SD card) - or reset to defaults - via one of the menu options (fingers crossed) such as Config Mode.

The Good News is that there seems to be a fair amount of spares (refurbished boards, and what-have-you) available for these monitors on line.

If you don't inspect ... don't expect.