Hi, can you check the following: when you press the button to open the tray, do you hear a motor running?
Thanks for your response to listen to the motor you have put your ear close to the unit then press the open button. If you have done so, then we have electronics problem. It is rare that electronics go bad. I think it might be a belt problem.
Can you take the top cover off and visually inspect the tray belt? Let me know the results.
Can you disconnect one of the motor power terminal and measure motor resistance. Also on the motor they might have info about power ratings for the motor. Using power formulary you can calculate winding resistance. The ohmeter should read close to calculated value.
If this is not possible apply a small DC voltage a cross the motor 5v suggested and see if it will turn. To avoid damage, you should have one of the terminal disconnected and system should be powered off.
So this confirm that the motor and belt are ok. The last thing you can is to find the op amp and replace it or bypass the switch and manually use +/-5 volts to open and close the tray.
Any luck on your end?
So, if the key gets signal from the microprocessor, then when you press or the second time, the polarity should change. Is that the case, what voltage are you measuring at the switch?
I think you have a problem where the power should change polarity unless there is a gear system that moves the tray. I would probably think that we have a much bigger problem that what I thought it was. Can you tell me how much space do you have on inside? You can build a circuit that can perform the same functions and use a relay to perform the change over. You can either use the open function or the close function but not both. Is this something you would like to explore?
You do need +/- to open and close. It is difficult to swap both terminals athe each instance without using complicated hardware