I would be cautious in this, if something has borked the installed on the engine, then installing SP2 may resolve it. Don't 100% expect it to work though.
If it didn't work last time it probably wont work now.
I would build a new server, install the SP and CU and bring it all up to date and then migrate the DB's onto it and bingo your done.
If SP2 fails you may need to get in touch with Microsoft Support and get your credit card handy if you don't have SA rights and support case rights on your agreements, usually around $500 a support case they charge.