I am sorry to hear that have had issues with the NUC model D54250WYK.
Based on the description, it seems you need warranty service for your computer. Please contact support at:
2 x Kingston ValueRAM- 4 GB - SO DIMM 204-pins - DDR3L - 1600 MHz / PC3-12800 - CL11 - 1.35 V - ikke-bufret - ikke-ECC -EAN nr. :740617219784 - 8 GB total.
Your memory appears to be ECC. The site below says ECC Memory is not supported.
I don't know if that means one should not use ECC memory, or just that the benefits of ECC memory won't be realized.
Just an observation I thought I would share. Not sure if it is relevant or not.