What sort of sensor does the unit use to detect open / closed status of the cover? Mechanical such as trip switch or button? Or an optical / IR sensor? Trip switches / buttons often just make enough contact with the plastic tab so if the sensor board or the door is off just by mm, it may not be activated. Optical / IR sensors sometimes fail or malfunction when dirt or debris gets into their tiny slots.

An exacto knife is too pointed. You need something rigid with a wider flat surface like a flat head screwdriver or any similar object. Wedge it under the melted ring and gently twist. The wide surface often breaks off as the melting process made them quite brittle. You just need to figure out a way to secure the replaced part back.

A. Does it make the attempt to pull the paper but it cannot? (You hear the sound of the paper feeding mechanism) Or B. It does not initiate the paper feeding process at all and just displays an error message? (No movement or sound of the paper feeder mechanism) If the scenario is A, you may have a worn out or dirty feed roller. The rubber on the feeder tend to get dirty and slippery thus losing their grip. You can clean them to restore their surface. Your printer might have a damaged feeder mechanism. If your printer is a top feeder, it is quite common for debris or small objects such as pens, coins or paper clips to fall into the paper feeder and can prevent the paper from coming into contact with the feeder roller. If your scenario is B, then there might be a communication error with the printer. Check your cable, try a different USB port, uninstall and reinstall the printer driver. Also check your print queue for pending print jobs.

You should bring that to a professional right away. Please do not try the rice method. It needs to be thoroughly checked and most importantly to get cleaned. Beverages, especially those with milk and sugar are corrosive and encourage mold growth.

Connect an external monitor to confirm that the laptop is indeed turning on. If there's display on the external monitor, you have either a damaged LVDS cable or damaged LED panel.

You can soak that in isopropyl alcohol to displace any moisture / water. Dry it thoroughly. I think you can test that without a CPU. Worth trying. Connect a small motherboard speaker next to the front panel connectors. Connect a CPU FAN. Connect the PSU. Turn it on. If it beeps then the board is alive. If the fan spins then turns off, there might be a short in the board.

That can be replaced but you need to have the right equipment. A regular soldering iron is unsuitable as you need to heat the entire connector uniformly to melt the solder all at once. A hot air station is what you need for that job. There are affordable hot air stations out there. You might also need something to magnify your work as those components are quite small, especially if you are going to check for bridged connections. These equipment would be a nice investment.

That is fixable. You need good soldering skills to fix that yourself. Should you decide to try it, your biggest challenge would be those lifted pads / traces and reconnecting them to their respective traces. You'll need a good soldering iron, good soldering lead (paste form solder / liquid solder would be advisable), solder wick, solder mask and uv light, good flux and small gauge wires or solder pads. You'll probably need something to magnify your work as those traces are quite small and close to each other. You'll also need a multimeter to check your work later. Looks like the connector itself isn't damaged so you can probably reuse it. Buy a replacement otherwise. Clean both the solder on the board and the connector using flux and introducing fresh solder. Use the solder wick to remove excess solder. Solder one end of your wire to where the lifted pads originally connected. Cut it leaving an excess to be soldered later to the connector. Solder the connector ensuring a solid bond to the pads that are not...

Try looking for a boardview file for that laptop motherboard. A boardview is much easier to understand than a schematic. Boardview have the same layout of parts like the actual motherboard and their connecting points. You would be able to see which parts are connected to. You can download the boardviewer program from here: Boardviewer As for the boardview file for your laptop, there are youtube channels that gives you download links to boardview files for specific models of laptops. Just input your laptop's model plus the word boardview.

If you dropped your phone in water, wrap it in a paper towel to absorb water. Putting it in rice does very little to nothing. Also, do not try to switch on your phone unless you are absolutely sure it is completely dry. A short might occur and you risk further damage. If you know how to, it is better to open your phone and clean it with isopropyl alcohol to displace the water. However if you do not have the right tools or skills, take it to a phone repair specialist.