Before you do anything spend some time searching the internet for you particular make/model of fridge. Look for a service manual. If you find one there will be a way to run diagostics on it.
I have a 2017 Samsung RF18 and found a manual for mine. It explains how to run diagnostics on it
Also look for common problems with the make/model, chances are you will find the exact same problem and the fix and possibly a YouTube video showing how to fix.
A friend of mine had a ~10 year old whirlpool fridge. He called a repairman who said it would X$$ for a service call and probably $XXX to fix and said it probably wasn't worth it. He called me and told what was wrong, did some searches, found two common problems, one was a cheap easy fix that was worth trying, local company had the part. The didn't fix it. The next fix was a control board, ~$150 from Amazon. Friend thought it was worth trying figuring he could get a board and send it back if it didn't work. So he ordered a control board and I sent him a link to a video on how to install the specific instructions on steps as it did require a sequence of button pushing for the fridge to accept it. That fixed. Only real problem was that he had already ordered a new fridge before calling me and so now the old one is in the garage for BEER
So take some time, do some searches. You may get lucky