peterwhi Said:
"won't turn on: [...]no, after the trashing and bin emptying, still no go. The BT is turned off and the buttons remain greyed out. [...]assuming your advice now is to ditch the system (or something) and restore from a backup. But I do have ™ backups."
-------
Ditching the System:
Yes. Ditching the system seems a way to go about solving this. Consider performing that, but as a last resort, only.
Reinstalling the macOS Anew (From Scratch):
Perform the following in the order provided:
I. Format the Drive - Install Anew:
Are you concerned of losing data? If not, proceed with a fresh install.
To Do So:
- Boot: into Recovery Mode
- Select: Disk Utiltiy
- Select: [the Drive]
- Click: Erase
- Click: Back button
- Click: Reinstall the MacOS
- Proceed from there as necessary
II. Once Installed...
Contact the developers of all of the software you had installed. Request a new license key, informing them that your computer crashed.
III. Securing Passwords:
Keep a handwritten, hardcopy of you password(s), and store it in a location that only you are knowledgeable of, and only you have access to. Do not share this information with anyone whomsoever.
IV. Backup your Mac:
Create a Time Machine Backup, that way, you can have something to restore your Mac from, should anything go wrong with the install. Use an external hard drive that is at least 1.5 the total storage capacity as that of your internal hard drive.