NanoPi R5C not booting

I recently (last week) bought via Amazon a NanoPI R5C 4+32GB with wifi .
When i boot the NanoPI the SyS LED keeps flashing. On the website it means that it’s installing itself.
I tried booting with a 8GB SD card that i flashed, but it is still the same result.

When connecting to a HDMI it stays black.
i added a video so you can see what i see.

Can you please help me with it?


First of all i want to thank youyeeto company for the quick reply on my question. This weekend i ‘played’ around with the NanoPi R5C. first i detected i was using a faulty network cable. Secondly my SD-Card which writed succesfully, also broke down. so lets say it was not a succesfull day.
After using a new network cable with a good RJ45 connector and new SD card i was good to go.

best regards,