Answer to "Why a button of my OP-1 doesn't work?"Take it apart, look at the Board under the buttons check to see if that area is worn down. Check the back of the board and see if the solder is good or if you have any burn marks. If these buttons are meant to rotate then you should check if the mechanism is loose from the board or damaged.
Answer to "Why does the hairdryer just stop working?"Yes Overheating will shut off at certain time. If this didn’t use to happen, make sure air intake filter (back side) is clean . Low or no airflow means quick overheat If clean then probably fuse is worn down and should be replaced
Answer to "Freezer is cold but not cold enough to freeze"Very possible that your low on refrigerant. I believe Kenmore has a 10 year warranty on the compressor so you should call them first. If your line doesn’t have a service valve to check and/or recharge with refrigerant adding that service valve will void the warranty. There may also be a very small leak in the system, you can opt to do a Leak Seal Steps I would take: 1) If Compressor under warranty - Call and have it shipped to you 2) In the mean time. Add a service valve and check refrigerant level - If low - then recharge 3) if issues continues - do a Leak Seal Repair at this point it will be the only way to salvage the unit. A lot of companies wont do that job for you since , sometimes, if the leak seal doesn’t hold you’ll need to replace the unit or continuously recharge. 4) Always check Thermistors make sure they have correct readings . Hope this helps! Gino