Cannot open Photos from External hard drive

Hi. I bought a brand new 2 tb External Harddrive and was trying to copy my library from my Mac onto it, I've succeeded multiple times but every time I try to open the Photos library from the hard drive it says it cannot open and that photos has tried to repair it but failed basically....I don't think the hard drive is the problem as I was able to copy the "masters" from another external hard drive onto this one as well as the masters from this Mac. I really don't know what to do, I'm getting frustrated, I will not be using iCloud to store these files as theres too many and I can't keep them on my computer. Any help is greatly appreciated.