Can someone tell me how to get my 500v to use the new serial number and license I registered?

So I was using a free trial of 500v to test it out. It works great for what we need so we bought it.
They sent me a new activation code and serial number. I registered them on mysonicwall.com
I followed the directions that they sent. i went to https://x.x.x.x/cgi-bin/diag reset my license. Tried to reactivate it with the new serial like they claim and it tells me No, I can only use the old trial licenses because it's registered to that. I google and I find https://www.sonicwall.com/support/technical-documentation/docs/sma_100-10-2-getting_started_esxi/Content/sma-gsg-using-the-30-day-trial-converting-free.htm/ . Alright cool I log in to mysonicwall account and try to deregister like it says there. Only option I have is delete for the license not deregister. if I delete the license I'll lose access to it correct? is that the same as deregistering? and if I delete it will it let me register the device with the other license?
I also have asked support about this but I haven't gotten a response and I'm a sonicwall newbie.
Answers
@Sdrago305 follow the below
1: ) back up the config (just to be safe)
2: ) you need to register the new serial number in your mysonicwall account
3: ) change you view to Classic view on the SMA appliance
4 : ) /diag in the URL like below
5: ) on your mysonicWall account delete the original Trial instance/appliance (make sure you select the trial one not the new one you have just registered)
6: ) on the SMA appliance go to Licences and put in the new serial number and auth code of the new appliance
7: ) your new appliance will now be registered with the new serial number
N.B, create a backup again make sure you remove any back afterwards with old serial number in the filename.