We have a 3-year-old Frigidaire Professional series refrigerator/freezer; French door, freezer compartment below; ice and water through the door. Model No. FPBC2277RF5

Some months ago something started triggering the alarm in the left door; that's also when the water/ice don't work. It is weird because it is intermittant; a cluster of alarms in a 15 minute period then nothing for a day.
We are in a rural area of the Oregon coast. A local repairman came, replaced upper switches on both sides of doors. Didn't fix it. He returned and replaced the "user interface" control board in the left door. Didn't solve problem.
More recently, the alarm has been sounding and a letter code comes up where the frig/freezer numbers usually are. Hitting the mute alarm does not reset it -- I have to go turn off power to the refrigerator to reset it. This concerns me that more of it is beginning to fail.

I called a certified Frigidaire serviceman about 25 miles away. He said he had the same refrigerator, couldn't solve the same issue and he bought another one. He advised the same -- saying replacing the main control board at the back of the unit didn't fix his problem and it was a gamble that replacing it would fix mine. But, if I wanted a service call(s) and board replacement it would be about $500.

A new Frigidaire Pro Series unit is about $2,000. (We have a 2-year-old house with all matching appliances, so I want to keep the same look.)

Any advice before I spend either $500 or $2,000?

Frustrated in Yachats, Ore.