Help. Hi have borrowed a friends compressor mercedes whilst my poor old holden is in the shop

Question

Hi have borrowed a friends compressor mercedes whilst my poor old holden is in the shop being repaired. The owner involved is overseas and all of a sudden the radio has just stopped working, including the phone etc. The problem is that the lcd stays on and I think it may be frying. not good for the friend about to return, Rang the dealer who told me to bring it it for diagnosis $$$$$. Seems to be frozen is there a button I could have pressed