I have 2 QIDI printers 1 just started changing the plate temp from 85 to 100c it has changed on all files on the sd card.

I swapped cards the 1 printer reads the cards correctly the other changes plate temp to 100 on every print.

Suggestions?

Which QIDI’s? Let both printers cool down for a long time so the beds can come to room temp. Probably several hours. When there, see what each is reading for a bed temp. Depending on the printer, go to monitor using the printer control panel to see the temps. If the temps are off between the printers by that approximate amount then the bed heater needs to be replaced.

I would contact QIDI on this also. If these are fairly new they will probably take care of it.