Cloning a HDD to SSD is not recommended because of various issues like this. The speed difference I believe is what kills it.
I suggest putting windows onto a bootable flash drive and installing a fresh copy onto the SSD.
Thanks for the reply
Yeah I did some reading re: HDD to SSD cloning and I read that the speed differences can be sorted afterwards using GParted (I think) or before by setting the alignments for the SSD using command prompt.
Anyways, the reason I didn't just fresh install is because my download link for the OG copy of Win7 seems to be broken, so I was more wondering if it's possible to fix the bootmgr issue as everything else seems to be in order! I could be wrong, of course.