42inch laurus tv very hot on right hand side?

Check (compare) the left and right rear deck lift links. Likely one has become detached or otherwise is loose.

See Cutting Deck Removal in Service section of your owners manual.

https://www.troybilt.com/en_US/prior-year-models/bronco-bronco-42inch-troy-bilt-riding-lawn-mower/13WV78KS011.html#/Troy-Bilt/13WV78KS011_Bronco_(2014)/Frame%2c_PTO_%26_Lift/205ecc55-4004-487c-ba7c-45eec1ba0efb/893227c6-4841-40b6-b0b5-58f600cc7df9/y

A fiber optic cable carries infrared light path only. It's a digital signal, you can only connect this to equipment that has an optic connection. Adapting it with any kind of analog jack just simply won't function.
laurus tv images Google Search

checking the Google images of the Digital module does not show a tos-link connection for the module.

It's held in place by 2 or 4 screws, check the back of the TV. Also make sure you have at hand the installation manual.

Hello Depending how wide the line is their could be two possible causes.
I have two questions for you.
1. How wide is the line.
2. Does it run from top of screen to bottom of screen?
If the line is thin a single strait line then it is possible the PDP has gone Bad (Panel). (Screen). The screen will to be replaced.
If the line is at least 2 or more inches wide then its a buffer board which can be replaced. LG calls this board Hand insert Boards or display driver boards..

Your info doesn't indicate if you have a good onscreen display or not. If you do the problem is highly likely to be on the IO board on the rear patch panel of the tv. Replace this board and it should take care of the problem.

If you don't have a good on screen display the two common problems are either on the power supply module or the digital control module. Samsung is known to have problems on both these modules and an electronics technician should be able to remove these modules to inspect for cracked solder joints, or out of tolerance electrolytic filters.

If these conditions do not exist on either board then the power supply board should be replaced first before replacing the digital control board. Search for a vendor that will offer you a full refund will a small restocking fee if the board does not take care of the problem.

main power switch -underneath screen on right side

These capacitors are on Hyper Board. You have to replace in order to fix the problem. See the link: http://www.diyforums.net/projection-tv-lines-1327.html

Sadly, the plasma screen is failing. The green strip is no longer functioning properly and the failures will continue to progress.

If still under warranty, get it exchanged.

It sounds like it's the inverter panel which lites the lcd back light.
If it's under warranty, try to replace it, or take it in for svc.