Troubleshooting advice requested, because the LED blinking
constantly supposedly indicates that the heater is wired
in reverse (which really isn't very likely, so I must be
misinterpreting something obvious).

Heater worked last year (AFAIK).

It just started getting cold in California, so, the heater power
was turned on, and ... and ... and ... uh ... um ... no heat.
https://c4.staticflickr.com/8/7508/1...4311f464_k.jpg

Thermostat batteries are good:
https://c1.staticflickr.com/9/8595/1...3c98abbd_k.jpg

Heater power is on and the blower blows but the red led blinks
at a steady pace forever.
https://c4.staticflickr.com/8/7513/1...4a54e186_c.jpg

Checked that the switches inside were all on:
https://c4.staticflickr.com/8/7510/1...c399d625_b.jpg

Checked that the fuse on the circuit board was good:
https://c1.staticflickr.com/9/8672/1...4a6d21f8_c.jpg

The sticker says constant flashes indicates reverse wiring:
https://c4.staticflickr.com/8/7505/1...4f42e6c5_c.jpg

But, there's no way the wiring was changed between last year & now.
https://c4.staticflickr.com/8/7540/1...2d8775fe_c.jpg

Here's what it looks like inside:
https://c4.staticflickr.com/8/7561/1...7f78bee3_b.jpg
https://c1.staticflickr.com/9/8561/1...7cc1f787_b.jpg

I don't know where the model number is, so, I don't have a manual
yet.

Debugging suggestions are requested, and very helpful. Thanks!