Yes, the idiot part can be directly applied to myself for believing them in the first place, no need to point it out further but I wont mind if you feel the need 
For the second time in the last few months I've been called with a tech issue and have during the process of diagnosis asked the client to check that all the connections to and from in the first instance a monitor and in the second instance a powerline adapter were securely attached with power cables connected and switched on. Both replied in the positive leading to further troubleshooting steps of which both involved me attending the premises to double check dead equipment before ordering replacements.
First instance, monitor plug was not plugged in, funny that seeing as how you informed me over the phone that it was a) plugged in and b) switched on.
Second instance, powerline adapter was switched off at the wall, again odd how that happened as you told me it not only plugged in but was indeed switched on, you even had your sibling check it too.

Sigh...

For the second time in the last few months I've been called with a tech issue and have during the process of diagnosis asked the client to check that all the connections to and from in the first instance a monitor and in the second instance a powerline adapter were securely attached with power cables connected and switched on. Both replied in the positive leading to further troubleshooting steps of which both involved me attending the premises to double check dead equipment before ordering replacements.
First instance, monitor plug was not plugged in, funny that seeing as how you informed me over the phone that it was a) plugged in and b) switched on.
Second instance, powerline adapter was switched off at the wall, again odd how that happened as you told me it not only plugged in but was indeed switched on, you even had your sibling check it too.

Sigh...
