Please try another memory part number and if possible just one memory stick at the time. Another troubleshooting step you can try is testing a different AC adapter in case the one you have is not working properly.
I was able to try some backup memory as well as an alternate power supply. So far no effect. Currently my hunch is that either the bios's needs to be reset to default or the unit is toast.
Please try disconnecting all components from the NUC and disconnect the battery for 5-10 minutes. Here you have some documentation about it: