According to the service manual, a sequence of 3 blinks indicates a lamp door or lamp problem. So I popped open the lamp access port, opened & closed the lamp door, put everything back together, nothing changed. Next, I repeated the above, along with removing & reseating the lamp assembly itself. Re-assembled everything, & the problem was solved. Apparently, the lamp assembly had somehow come loose by itself. Or, the lamp door latch & associated micro-switch just needed to be cycled several times.:flex::clap: