Pentax What does Flashing E mean in window ?

I opened the back. the film roll wasn't in correct order. so I wound a little & closed. now seems ok!

I experienced this with a trusty film-based Pentax 105 Zoom used as a backup on a European trip. It was frustrating that the big "E"
warning was not covered by the otherwise complete manual, and
I was on a cruise with no competent camera shop to advise. I had
loaded fresh film AND new batteries from a reliable supplier before
leaving. So: (1) manually rewound the used film, replaced with new, and (2) checked to see if the lens cover was properly deploying when the camera power was turned on. This turned out
to be the problem!. Cover needed a little fingernail flick to open fully, the "E" warning disappeared, and I got 8 superb rolls of
Italian pictures.

I think it means the film hasn't loaded properly. I had this and opened up the back and the film hadn't wound so it wasn't exposed. Anyway i just wound the film around a bit and shut the back and it turned on like normal. hope this helps.