Errors DMG CTX620 Heidenhain Controller

Hoping for some help, I'm at a bit of a loss with our 620 lathe, We have multiple visits from service engineers to no avail. Is anyone familiar with the attached errors and possible reasons for it? It hasn't ran for over a year now it started with a chuck/clamping issue and escalated top where it is now.

If we switch it off for a while the errors clear and we can run it for approx 50 minutes before the errors reappear and it stops working again. Any help/ideas would be massively appreciated.

Thanks