Water in bottom of freezer

I have an ice build up in the bottom of the freezer and the drain tray is frozen also. I think that the heater may be bad I don’t want to take this apart twice can someone tell me if that heater is for the tray and how do I test it.

I cannot find info on this model number. Here is what comes up when I search
Replacement parts for MSD2464GE models | AppliancePartsPros.com
Please check iy.

If the unit is otherwise running OK then I would say the heater and defrost system are OK. That is why there is water/ice at the bottom of the freezer.

Sounds like drain tube is plugged so that the water from the defrost cycle cannot drain into the drain pan.

I would check that it is clear.
If plugged a turkey baster with warm water, an air compressor with low pressure or a wire can often be used to clear it.

Also check that it is not plugged with dust etc. at the drain pan end.
You might as well clean the condenser/compressor fan and the condenser coils while you are down there.

If it looks like stuff is growing in the tube I would flush it with a 10% bleach solution. This should kill the stuff and let you flush it out. You may have to do this several times, let it sit for 15 minutes or so between flushes.

Be careful that the drip tray does not overflow and empty the drip tral after you are done.

Also check that the drain pan under the evaporator coils is clean. Dirt/crud here can slow down the water flow giving it time to freeze.

Be sure to unplug the unit while doing this.