Sounds like the wire is broken inside the cable and thus you have a loose contact. There are really only two options to fix this: - find the approximate location of the broken wire, cut it out and mend the resulting two ends together - replace the whole cable altogether
The printer head is probably dirty. Epson has a Nozzle Check and Head Cleaning option in their software, so you should try that first. In case that doesn't work, you might want to look up a guide for your specific model on how to remove and clean the printer head manually.
My best guess would be that you shorted something out with static electricity while handling the board. If that is the case there is no easy fix if any depending on which part got damaged. But of course that all depends on your environment. Do you have carpet on the floor? Do you like to wear woolly shirts? If so you probably should discharge yourself by touching something grounded like a metal sink before working on hardware.
The screen you see is actually two parts: - A seethrough Touchscreen, which is brittle and can shatter - The actual Screen So you should get a replacement touchscreen and look up a guide on how to replace the touchscreen for your specific phone.
What you need is a disassembly video, most of the time youtube will provide you with a decent one. Quick search i found following: https://www.youtube.com/watch?v=eLtzpuS-qhs Usually i would recommend ebay for replacement part, but haven't found that part on there this time.
Ebay is the best place to buy replacement parts of electronic devices. Quick search already resulted in a few LCD replacement screens for about 10-15$ and some more expensive were the backlight is included.
Best place for replacement parts of electronic devices is ebay. Found over a dozen of your batteries on there. While most of them come from china and are little bit less quality, they get the job done and is definetely better than buying original one for double or triple the price. Three years ago i bought one from China and while maybe only 80% from the original capacity, its still working fine to this day.
Sounds like that your END button is stuck, either physically slighty stuck down or short wired by something that went under the key like a fluid, maybe a squished little bug. For now your best bet would be to CAREFULLY remove the END key from your keyboard and clean whats under it.