ok...
So... it's a white screen. That indicates a server side error.
This should generate a log.
Usually, a file called error.log, errorlog. or something similar.
no, 4.8.3 does not make sense.. but neither does 7.2.7
SMF 2.0.14/15 requires 5.4 to 7.1 -- I recommend 5.6 for now and possibly 7.0 or 7.1 once everything stabilizes.
on a slightly related note.. ALWAYS take a backup before each and every mod or patch.
If all else fails, you might be able to ask your host to restore last night's backup (assuming the host does nightly backups)