Hi guys I've been busy swapping my old agu for the new one after my oil pick up pipe blocked and seized the engine

the swap has gone really well and everything is finally back together again

. However I went to start it on saturday and it just clicked but didn't turn over

I herd everything prime etc as normal but didn't turn over, i wasn't 100% where the earth went as a start? ( The earth that feeds from the battery tray.. I can't seem to locate where this goes, and I was wondering if it matters? And does anyone have any ideas as to why its not turning over? Just any suggestions please? I know I've had everything apart so it could be anything, but at least if ppl can give me ideas then I can keep checking things. Thanks in advance.