UPDATE #1:
Somewhere, someone recommended LG and/or Vizio as possible matches for late model RCA televisions.

In my URC database, LG #286 discrete POWER OFF works. The corresponding POWER ON does not, nor do any of the direct input selections.

I went through all 27 LG code sets. None of the discrete ON or direct input selection codes worked. Now to try the Vizio codes...


ORIGINAL POST:
I have an old URC MX-810. Not the latest remote and certainly not the latest software. The latest software release was 5-27-2013!

I bought an RCA RTU7877 from Wal-Mart on Black Friday. Got a heck of a deal.

None of the RCA IR options in the MX-810 database work. They won't even power it on.

I would prefer not to use the learning feature unless I absolutely have no other choice.

I am able to use Hex Codes to create individual keys if necessary.

I'm using it in conjunction with a Yamaha AVR, so the only controls I really need are:
Power ON
Power OFF
HDMI4
TV

Details about the TV: it's a 2015 Samsung panel in an RCA chassis. The factory remote is terribly simple and would make programming the MX-810 far from ideal if I cannot find the appropriate IR database.