Hi @falcoch ,
What is the full model number of the microwave?
If possible check all the connections from the LCD unit to the keypad for any dry joint connections.
If it looks OK, check on the back of the LCD unit for any information as to make or model number of the unit itself.
If there is any info, search online using the info and check if any results.
If none there, the only option may be to buy a new keypad assembly.