The old Brainforce V IPB forums have successfully been migrated over to Enjin! It'll take a few days or so to get everything settled, but for now all existing content (Minus a few threads and posts from the past few days) has been moved over and the forums are now usable!
Regarding user data; if you registered to Enjin using the same email you used for BFV, all your data from there will now be associated with your account here. If you didn't use the same email, or if you have yet to register on Enjin, you should be able to use your BFV details to sign in.
And on a separate note; if you have yet to link your Minecraft account to Enjin, I recommend doing so in order to sync your server status with your profile here. You can link an account by heading to your profile page and using the Add a Character option there.