The freezer is thawing and the refrigerator is not staying very cold

Below link will help you .
However i suggest get a repairman if initial checks dont solve your problem .
However take a note of the points just to be sure hes doing the right thing .
https://removeandreplace.com/2016/11/08/my-refrigerator-wont-stay-cold-food-in-freezer-thawing-what-could-be-the-problem/

What is the model number of your unit?

My first guess is defrost timer, is stuck in defrost, if you can find it, turn it, and if the compressor and fans turn on, you got your answer.

Hi,
The defrost is sticking and staying on for too long...
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heatman101

With the defrost timer being replaced already it sounds as if the repairman is not looking at the real problem. Unit works for 2 days then things start thawing. Hint Hint... it is not defrosting. There is a heating element inside the freezer section attached underneath the internal tubing that melts the ice every 6 to 8 hours via the defrost timer depending on the defrost timer installed. To prove that it is not defrosting..... just unplug the unit and place a stand fan blowing into the freezer for about 90 minutes. I would bet that once you plug it back in it wil work for 2 days and the problem once again repeats. With 2 calls on the same unit and you still have the same problem I would be calling the service people back and demand they fully troubleshoot the defrosting element and thermostat. Personally this is an unstatisfactory performance of an in home service by a repairman. With the exception of a new part if required, they should wave any labor and service call fees.

Possible defrost problem. If the evaporator coils behind the back panel of the freezer are icing up because of auto defrost failure that will stop the circulation of cold air.Since you've already replaced the motherboard Checkdefrost heater, defrost thermostat
How to check everything
http://www.acmehowto.com/howto/appliance/refrigerator/refrigerator.php

What is the solution? What can we do to engage the refrig. again?

have oiyu ried to thaw it out then plus it back in? also is there anything that could be blocking the air at all? The easiest way to thaw a freezer is to take a shop vac and turn the air around and blow it on the coils to thaw out the ice. go ahead and make sure t=hat its cpompletely thawed out them turn back on and check the air flow afrom the fan after its ran a little bit. Don't rae until your problem has been resolved then rate the best solutions please. Thanks for using FixYa.

the temp control thinks its cold enough to stay off so you need to have the temp in home warmer so it will cycle / atleast 60 / larry

sound like a ref cold control issue and this will bee the total control that will have to be replaced