I hate to say this, but more then likely you just got blown off.
The tech could not see an issue so he took a craps shoot to see if it will work.
Maybe it will, but if it is was working at the time the tech came over, he could not possibly determine it was a bad a receiver.
I am guessing that there is a good chance the issue may return. Hopefully, I am wrong but if it does, switch the boxes around.
If the problem continues in the same room, you know it is probably a cabling issue.
If the problem follows the receiver, then it is a receiver issue.