Thanks for joining the NUC community.
I understand the NUC does not boot when using 1333 MHz memory at 1.35V.
I have checked specifications of the NUC, especially memory area, I have noticed the NUC model DN2820FYKH comes with an Intel Celeron N2820 which supports 1066 MHz memory speed.
Only NUC models with Celeron processor N2830 will run at 1333 MHz
See here for more details:
Intel® NUC Kit DN2820FYKH — System memory
Allan.