i dont think there are calibration options for batteries. happy to be corrected. The battery should just be a battery as long as its made for the device. I have purchased 3rd party batteries that work fine however they tend to not last as long as genuine parts (in my experience)

Older LCD TVs usually have a series of fluorescent tubes providing the backlight for the TV. They are controlled and powered by a circuit board attached directly to the panel. While it's possible to repair this circuit or even replace the failing fluorescent tubes, the effort and time are vastly outweighed by the cost of a new LCD TV

Usually its because the replacement hardware is being manufactured by the same people selling the new phone and they want you to upgrade.

This is a common issue, assuming things liek speaker phone are working normally and the phone is behaving normally otherwise. You can clean the earpeice grill with Methylated spirits from a hardware store and an old toothbrush. Wet the toothbrush with the alcohol and brush the metal grill of the earpeice, this will remove dirt and grime from the metal grill, allowing sound to pass through again.

Assuming the DVD player used to play DVD's, i would think its likely just a motor fault in the disc assembely. *warning, plugging in a unit with the case open can result in a touch shock risk, please be catious around exposed electronics especially where the power lead comes into the device and the surrounding electonic components. you can test this by (1) powering down the unit (2) remove the cover (3) plug the unit back in (4) load a dvd (5) confirm weather or not the disc is spinning. If the disc doesnt spin, give it a push and see if it start up from there. this will confirm a motor fault in the reader assy. If the disc is spinning but not reading, then you are looking at a laser fault or possibly logic board issue. after powering back down, try things like reseating cables, or carefully inspecting and cleaning the laser lens is isopropyl alcohol.

firstly, does the 2DS power on when plugged into power? If it is working on power but not when unpluged you likely have a bad battery. you can take this out and measure it with a multi meter to see how much charge it is holding, batteries in DS's and other electronic devices can go "low" meaning they want charge properly and never store enough power without being charged by an external charging station. If its dead/dead, then refer to some of the troubleshooting guides on this website. Nintendo 2DS

do you still have the old laser? put that back in and test. as you stated it was reading all games except one before the replacement, so its likely not faulty. Unless you are running a "cracked" WII, its possible the game disc is from a region outside your area and wont read: https://nintendo.fandom.com/wiki/Regions Usually the region is printed on the label.

Does the keyboard itself have a model number on it? searching for spare parts on that number should yeild some results over the model of your computer. Failing that replacing with a 3rd party wireless mouse and KB combo wont put you out of pocket. Microsoft sell wireless KB/Mouse combos with USB adapter that should work seemlessly with that device.

It sounds like the LCD screen is physically damaged. if you are happy using an external screen in the meantime it is a suitable alternative to replacing the monitor but obviously limits portability.

The motherboard or mainboard will contain all of the configuration of the phone, it will be very likely that if the board is replaced correctly it will behave like a new (out of the box) device and not have any of your configuration, like face ID. Be sure to backup if you can before swapping parts.