Weil McLain GB-6 electrical (?) issue

Anoelg

My boiler died on Monday with -10 outside.  The control panel was dead - no lights. I called a tech who diagnosed it as a control panel problem.  He also told me there was an incorrect fuse -15amp and that boiler maxed out at 12 amps. I bought and installed a new control panel UT 1013-200, and 10amp fuse, and it did not work.  I called them again.  They came out, looked everything over and said it was a low voltage issue and the transformer was not supplying 24V to the panel. He replaced the transformer and the boiler fired right on.  All was great.  Few hours later and the boiler is dead again. No lights on the panel.  Any ideas?