Some panel buttons are not working on my LG LMV1630ST

This is what I did. Had to do this a few times, but the last time haven't needed to for a while.

Pull the oven out from the wall. Turn off the power or unplug. Behind the control panel on the back, unscrew the upper access panel. You will see large ribbon cables connected to the touch control panel that the touchpad operates. It's pretty obvious what the large touchpad ribbons are. Disconnect those. You will have to unsnap part of the plastic holder that clip the ribbons into place. Those ribbons get full of steam and particles and as a result have a poor connection to the touch panel. Wipe them off with cotton balls or paper towel keeping them free of lint and such.

I originally used rubbing alcohol but you have to be very careful not to rub off the metal connections on the ribbon. If you start to see any removal the metal on the ribbons, stop right away. If you don't want to use alcohol, use water instead but get them clean and then dry.

Reconnect the ribbons making sure they are secure with the clip, and test the panel. What I did this last time is used a little bit of electrical grease and put a thin layer on the ribbons.

That has solved the problem for several months now and I haven't had to repeat this process since that time. I did actually have to trim the ribbon ever-so-slightly with a pair of scissors since the first time I did this a few years ago I was too aggressive in rubbing the electrical contacts clean. I ended up actually removing some of the electrical contact material at the end of the ribbon the first time when I was too aggressive.

Good luck!

The problem is in the keypad control board and must be replaced, I would consider cost before you allow the go ahead.