Emergency no heating call Framingham ma

Responded to a no heat call in Framingham ma and found a really clogged, dirty filter which caused the high limit switch to shut down the gas furnace on a fault code. In addition the 3 amp fuse was blown on the circuit board and the batteries were dead on the thermostat. We replaced the filter with a new 25x16x1 filter, we installed a new 3 amp fuse and new AA batteries. Also we had to reset the fault code and restart the furnace and checked normal heating operation.