Hi Paul,
If the LED is flashing while the flapper is closed, the beam is not blocked and the door light switch is not pushed in, then the problem is a bad optics. The solution is to replace both optic boards.
- The optic boards kit
Part number: AP3137510 
Here are the breakdown diagrams and
Replacement parts for Whirlpool KSRP25FNSS00 REFRIGERATOR | AppliancePartsPros.com
Gene.