I had the same problems on my last A-350 flight, after several flights where it worked perfectly. After one hour the IFE broke down. Going with the pacient SFS through the various re-starts I learned a little "secret". Normally, the system is set in a way that you control it through the hand held device. My problem with it: it does not allow you to access the various sub-menues of the air show - and the airshow is my peferred entertainment programme. Most of crews do not yet know about these features. So, to access them you have to move control from the hand held to the (touch) screen. He explained me that you have to press the on/off button for some seconds to initiate the re-start of your system. Then you have this little circling thing. After some time of circling the face of a flight attendant should appear. Put your finger there and after some more circling the system should prompt you on whether you wish to transfer control from the hand held to the screen. Unfortunately, I could not verify this as the system wass off..I will try it in two weeks on my next flight. Has anyone tried this already?

Btw: QR compensated me with 5000 Q miles which was fine for me