ESXi 6.7.0 on Dell PowerEdge 440

I bought a server Dell PowerEdge 440 a year ago. I downloaded ESXi 6.7.0 (build number 11675023) made for this server from dell.com. All was working normal but yesterday I restarted the host and now my VM is not working. A license key is needed. I read all about licensing and more but I can't register my product in VMWare.com. (when I downloaded the iso file from dell. com there was no option to register the free product.) On a Licensing page in my host is written:

Key: 00000-00000-00000-00000-00000

Expiration date: Never

Someone can help me with this issue?

Thanks a lot in advance!