Not getting any reading from control board on GLFU1767FW2 upright freezer

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From what I read, the "L." that you see on the control panel indicated that the controls have been locked. According to the manual if you hold down the "alarm reset" button for 3 seconds the "L." will disappear allowing you to control the temperature again. I don't as of yet know what is causing your overall problem though...

If you had the door open for that long you will need to unplug and allow the ice buildup that happens when door is left open to thaw. After this you need only to plug the refrigerator back into the power source.Let me know what happens It is not going to work correctly until this is done. Sea Breeze

Try disconnecting power for about 30 seconds, and then restore power. This will reboot the control and maybe restart.

NOTE: This
is a multi-solution answer since I don't have all the tech from your question to pinpoint your problem
But the solution is in here generically, if you read and study the solutions very,very carefully.
First I would check cold control. Thats where you turn it off, if your temp is not warm. it can
be defective and not shutting off. If your temp is warm proceed with the following.
I would check the fan in the freezer. Listen to see if it is running
It moves air to the ref from the freezer
Then check to see if freezer control is turned WARMER, which makes the Ref. colder
Also this might be a common Defrost problem, Ice
is not being melted by the defrost system.The fan can't blow through the coils into the fridge.
Take out back panel of freezer to check for ice buildup. The coils should be clean.
There are three components to a defrost system- a heater,heater thermostat, and a timer unless you have a defrost electronic card.
Its best handled by a Technician but you could possibly do it by taking your model number to the nearest appliance parts store and asking for the parts. They are mostly located in freezer ,behind back panel on freezer coils.except the card which is usually located in ref The parts store will have info
Also check fan undernearh Ref in the rear
Clean condenser coils underneath
Check cold control (thats where you turn it colder)
.I'm including my article on Refrigerator Repair for your help and convenience.;
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http://www.fixya.com/support/r5816737-fix_refrigerator_psychologically
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Leo Ponder
imufo2
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yes you need to replace the circuit board

it the timer

Sounds like the sensor circuit may be open. Here is the problem, either it has a board that's bad or the sensor is out. Ohm the sensor circuit and record the temp the box is at in refrigerator and freezer. then the ohm reading. Contact manufacturer or representative of manufacturer, and ask what the sensor should read at the temps you have.

Generally if you get a reading on the sensor circut the sensor is ok, and the board is out BUT not always. this is why you need the temperature and the ohm readings. Sometimes the wire diagram has a legend with these reading on it. Look all around the underneath and behind sections for an envelope containing the wire diagram.

First make sure you have a good 9v battery installed. If it is ok then the problem will probably be in the display board or the wiring connectors between the boards. CE is communication error. If your model has the electronic tempature control instead of mechanical thermostat the problem could be in there. My bet is a bad connection at display board.

It seems your temp. control board or thermistor is not reading the temps and just keeps on running and running. Can you lower it to the lowest setting and (with a thermometer) see if the temps actually get warmer inside (will take a day or two to warm up). As for the ice on the bottom if the drain for the defrost cycle is plugged you may be getting water inside which then re-freezes. Let us know what you find and we can go from there.