How to resolve "PF" power failure on an lg WM3431HW

Hello, I have an LG WM3431HW which is a combo washer/dryer. It is around 4-5 years old. It was working fine, then recently after completing the washing cycle and after a few minutes after the start of the dryer cycle. The dryer cycle shuts off without error (power to unit still on). We opened up the top and cleaned out all the lint caked on within the dryer duct and made sure lint trap off drain pump in front was cleaned. We started again and received a DHE error. We confirmed the dryer element was heating up fine. We also tested continuity to through the dryer thermostats and it had continuity. Also confirmed appropriate voltage over dryer element. We then took dryer duct fan off, turned it upside down and re-connected to make sure it was turning properly. It seemed to start and stop and it was also very hot so we thought there was a problem with the fan so we replaced the fan, and to be safe, also replaced the thermostat. Once that was done, a few seconds after the unit goes into the dry cycle, the cycle stops and shows a "PF" power failure error. We checked all connections we can find but everything looks connected correctly. We eye-balled the power board to see if there was any burn spots or anything else noticeable but nothing. We also eyeballed the power filter for the same but nothing looked out of the ordinary. The heating element was hot and confirmed the dryer fan duct was revolving, albeit for a short time. It seems that there is something tested after the heating element is started and the fan revolving, that is not working and which is telling the unit to shut off or "power failure". We had also unhooked the dryer thermistor to see if anything looked unusual but looked fine and re-connected. What else can I check and what part is likely to be at fault ? Since the wash cycle runs fine, I am hoping the power board is fine. Thanks