Are you getting the normal hours of run time out of the cart? If so, the charger is doing ok. If run time has become shorter, suspect a bad battery or more and do appropriate charge-and-load cycles on your batteries. Note that batteries have to be disconnected from their 24- or 48- volt setup in the cart to test each one correctly.
Be sure your setup on the scan is set correctly: If it is set to “Antenna” instead of “Cable”, the scan will not read correctly. (Some sets my have “On Air” instead of “Antenna” but you have to make the switch for the scan to work properly). Still not working? Try plugging in an antenna lead, or even a stripped-back the insulation piece of coax and scan under the “antenna” setting if in an urban area. If the tv picks up some signals, perhaps your cable line is dead?
Either battery was defective from factory, or it has gotten hot on it’s initial charge. One fix that seems to work half the time for me come out of a Popular Science issue yeas ago: Remove battery from machine. Place in freezer for at least two full days. Plug back into charging system right after removal. (Moisture will be coming off the battery for a bit—-keep the battery out of the machine so no moisture damage’s it). Monitor the battery temperature by touch while it is charging. If it starts to feel unnaturally warm, unplug the charger for an hour or so or until the battery returns to room temp. Restore charge and monitor temperature again. Repeated heating up would suggest a detective battery. Be sure battery is wiped completely dry before re-installing it into your machine.
Usually three different micro-switches work off of your door latch. Usual setup: 1 for light, 1 for safety on low-voltage side of your power supply (where your problem probably is), and one for the high-voltage side. Remove your cover (unplug unit first please), check the physical operation of all visible micro-switches as you open and close the door. If they all are changing function as they should, use an ohm-meter to check each switch for continuity. Remove one lead off each switch so the meter isn’t reading into the power supply. From what you describe, 9 times out of ten the problem will be in the microswitches. Having to reposition one or more switches is not unheard of as the microwave ages. Good luck… And never work on a microwave with the cord plugged in. (That’s why I look like 103 instead of 43!)
It sounds like your reading head for your scanner is not returning to it’s “home” position. If you are halfway not fumble-fingered like me, you can gin entry by usually removing the top glass. You should be able to get the head into it’s '‘home” position and check the cogged belt that moves it to determine if the belt just jumped a notch or if you have worn belt or stepper-motor problems. Check for a mark on the belt made by a marker at the factory when your unit was first set up. This will help you determine what’s going on. If it checks out mechanically, try reloading your driver software for the HP. And be careful around any of the printer’s so-called “secure” home pages for software downloading—-they seem to be a heavily targeted area for con artists with their own software and programs.
For checking speakers, I use a multimeter with a resistor measurement to check that the speaker is not shorted and I displaying the correct impedance: 2ohm, 4ohm, 8ohm, etc., whatever it is supposed to be. With the speaker leads disconnected from the amp, of course. Then take a one and a half-volt battery and touch your speakers leads a few times. You should get a “pop” noise that sounds relatively clean—-a bad speaker will give you a harsher “scritching” sound if the voice coil has been overheated and deformed. Note: a one and a half-volt battery will not harm your speaker if not continuously applied. Switching speakers around, or “borrowing” one from something else will tell you if you have amplifier problems.
I have the same issues keeping sound going on my less than two-year-old Dell XPS-series laptop, so don’t feel bad! Tried going the downloading of new drivers, etc., but found the easiest way: The sound drivers seem to get corrupted very easily on a system running the Windows 10 (Windows 10 Pro Series not excluded). Entering the system control and deleting the driver when prompted for an action, then reloading the same file back from the Windows 10 system has always resolved the “no sound or bluetooth” issue for up to a month or two, or sooner if you change outputs and inputs or add new devices. Trying this on your machine may help, but I’m not sure what other curves might get thrown by your Mac op system. Good luck—-let me know if that helps you.
Check your solenoid or float and ball assembly, however yours is equipped. If solenoid equipped, is it getting voltage? Is it a type that may be cleaned and checked by you? If float and ball, check and clean.
Sounds like your drive belt needs replacing. The old cassette car players were prone to this problem, especially in very warm or very cold climes. An aging main drive belt will slip and the direction sensor will be tricked into it's "end of tape---switch directions" mode. No easy in-dash repair, sorry. Player will have to be removed and disassembled to reach the belt. A good tech will also check the other drive belts, drive wheels and clutches while he's in there.