Repair Berliner Tear in the bedliner

If a plastic insert, buy Loctite "plastic bonding system". Then glue a patch of anything you want (milk bottle or other poly propylene or High density polyethylene (HDPE).

If a spray-in liner, bring it to a rhino-liner installer in your area for a touch up.

Unbolt it from the the frame if you have a bedliner do it from the underside....but, don't forget to detach your taillight wiring as well as detaching the hose the runs off the gas tank up to your gas cap.

could you use a heat gun to heat up the bed liner to put in a recess to make it fit

To add some class without getting gaudy, I generally do a minimal dress up by putting on a black bug shield on the front (wind deflector) and over the window rain guards (for side windows).
You can also accent the body using a blue and red or red and black pin stripe along the mid line.
A bit more difficult but worthwhile is to compound the lower rocker panels and remove any wax, then mask it off and use bedliner spray (black), blending it up to the fender flairs. This is not only a "dress up" but very functional as the rockers are very prone to rusting and the thick coating helps protect them. If you have stock steel wheels, you can do them up with bedliner as well.
I buy and sell Jeeps. Aside from making sure each one is perfect mechanically, I often do exactly as I outlined. Not only does it make them nicer to look at but It usually brings an additional profit and makes them stand out in a crowd.

In most cases you would have to take the liner out . If you cannot see the blots inside . You could look on u tube for a video on this it would help you a lot ,

you have to remove the handle. there you can gain access to the latching mechanism and rods connecting to the latch if you have a bedliner, you may have to remove the bed liner on the tailgate to get to the screws

Fords have a fuel shut off switch in the rear. It could be tripped when slamming the tailgate shut. In the bed on the drivers side you should be able to find the switch. Press it down to re-engage. If you have a bedliner this may be harder to find.

First thing: Try using the key to move to the locked and then to the unlocked position. If this works, open the tailgate... This also pretty much tells you what the root cause problem is, which is a pressed-in plastic post working its way out (see below).

If no bedliner, just remove metal plate inside tailgate and actuate by hand inside to open. If bedliner, first use a small screwdriver to carefully (don't scratch paint) push in latches at either side of tailgate to open/lower tailgate (if locking/unlocking as above did not work to lower gate and gain access). Next, use two blade screwdrivers to pry out the "buttons" that hold the ends of the tailgate liner where they wrap around the sides, then remove bedliner piece and metal plate, etc.

Once you have access to inside of tailgate, you will see how the mechanism works by pulling up and down on the handle while observing. You will probably find that the slide mechism that locks and unlocks the mechanism has been allowed to move such that it cannot unlock/allow movement of the latching mechanism. This is usually the result of the pressed in plastic anchor being worn/loose. I had some success with cleaning thoroughly with alcohol or brake cleaner, allowing to dry and then using super glue to hold it firmly in all the way. Still have to hold handle up when closing gate and keep key on hand to unlock every time opening, but it was a free repair...

There are two 10mm nuts on the backside of the light in the bed. If you have a bedliner you will need to pull it out of the way so you can get to the nuts. Or drill a hole in the liner after you locate the nuts.

OK God is here....ya have to peel the bedliner open and you will find 2 10mm bolts.....they release the assembly :)