A battery is always suspect until it has been charged and LOAD tested.

I have no idea what engine you have, but if it's a Briggs OHV, than you need to adjust the valves with the PROPER procedure.
The compression release is dependent on proper valve lash.

is it worth getting repaired if its not the battery

Yes, unless it has something seriously wrong with it.
You are not providing a wealth of information so far.
It would help to know the Brand and Model number of the engine (and that does not mean how many horsepower it has).
You could also let us know how you determined the battery to have "enough power to turn an engine" if your engine "does not turn at all anymore".
You might even describe to us some of the "issues you have been having for a few years" so we can ponder if any of that stuff could be related to the present issue.