Macbook Pro freezes after I enter my password The mac starts up fine and goes to the login screen. After I enter my password the losing bar circles once then freezes, followed a few seconds later by the cursor changing from normal to the frozen-working-stuff-out-wheel-of-many-colours. The mac then stays in this condition perpetually.

I will gladly accept suggestions as to a course of action.

RELEVANT INFO:

2008 Late, MacBook pro 13, running High Sierra

For some reason (which I'll gladly accept an explanation for) I cannot use any commands on startup, such as recovery, safety, and NVRAM, as it simply doesn't load anything. (I have a feeling that's related to me forcefully boot-installing the MacBook to high Sierra (HS) a few years ago, because originally it's spec wasn't up-to-date-enough to support HS, but am open to other ideas for the cause of that.)

There is no vital data on the machine, as I am operating entirely from Google drive.

I have the spare (so-slow-it's-effectively-non-functional) original HDD from the Mac (which I removed during a recent SSD upgrade.)

due to my internet speed being quite slow, I'd much prefer not wiping the machine and starting afresh, if it can be avoided.
ONE SOLUTION: if you've a spare OSX hard drive, re-fit it, and connect the SSD via SATA_USB cable. Boot holding alt, and select the SSD. It should be able to logon without issue. Next, shut the machine down, take out the old hard drive and refit the new, power her up, and the problem, for me at least, was solved.