I have a Summit AL54 fridge that is no longer cooling. Unit is only about 2 years old, professionally installed in a clean environment (bar in finished basement). I first discovered significant ice buildup and was able to partially thaw and remove a big chunk of ice through the back wall of the inside of the unit (so I didn't need to move it out from under the counter). I hoped that would fix it, but the next morning it still wasn't cool. Summit support thinks it's a coolant blockage and I need to hire a pro to fix it. Any do-it-yourself tips/suggestions before I do that? Thanks!