Backup Restore Failure

I tried to restore the shop using the backup created when I updated from 4.3.9 to 4.3.10 and it crashed the site resulting in:

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Internal Server Error

The server encountered an internal error or misconfiguration and was unable to complete your request.

Please contact the server administrator to inform them of the time this error occurred, and the actions you performed just before this error.

More information about this error may be available in the server error log.

Additionally, a 500 Internal Server Error error was encountered while trying to use an ErrorDocument to handle the request

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Is there anything I can do now? or am I doomed to start over with new 4.3.9 install?

Did you look at your error_log?