apple mac

Mac OS Sonoma apple calendar is giving me an Authentication failure, failure to authenticate with google please try again later, when ever I try to add google account to the calendar. any suggestions?

I have 2-3 old iMacs which I want to recycle. Is there a USB tool I can use to boot and wipe the drive? And, what keys do I hold down to boot from it? Thanks.

I don't normally repair Mac's but was asked to take a look at a friend's with everywhere closed at the moment. The machine is a 27" Mac Desktop model I suspect 2010-2012 (Bigger case with DVD Drive built-in) and the hard drive has failed. I have successfully removed the old drive and put in a...