Thanks for the post and welcome to the forums.
I wouldn't do anything that couldn't be un-done especially when the unit is under warranty. Electrical tape is the best bet since it is easily removed. I wouldn't paint the LED, but putting a tube or 'straw' over it as a cap sounds doable. The rear panel cover would have to be removed. Shouldn't be much of a hassle.
Either way, I wouldn't let this 'glitch' be a factor in your decision.
Free, abundant OTA television separates this country from many others. ATSC1 has only been in force since 2009. The wireless industry has enough spectrum. Enough of 'planned obsolesce'.