If the input power has only 2 wires then the machine is double insulated and does not need an Earth connection. As for performance will not deteriorate without an earth connection on most equipment.
An HDMI port can be bought new or can be found on many scrap equipment desoldered then refitted to your machine. As for the apparently missing components! it is likely they were never fitted intentionally by the manufacture’s. Looking at the print side if the pads are clean then this may be correct.
Use jump leads connect to another vehicle and start it up then connect to your flat battery in your car let the other vehicle run for a few minutes before starting attempting to start your own vehicle then close your window. Make sure you observe battery polarity.
Water is a conductor of electricity and if allowed to come into contact with PCB’s (printed circuit boards) then you do have a major problem especially if the TV is on!...or switched on after the event, I doubt that any fixers out there would take this TV on as a repair job.
Their is a special bit/tool that can remove stripped screw heads but cannot recall it’s name!…This problem can occur when the wrong screw driver is used to remove Philips/ Pozidrive type drivers but especially when the tool is not a snug fit and plumb with respect to the screw.