I found a fix on a generic chromebook forum:
Plug in your chromebook.
Hold down the Esc, Refresh, and Power buttons until the charge light turns to solid red.
Leave it charging for at least 4 hours. Charge light will turn green.
Now it can be turned on.
Eta: this worked on my chromebook plus.
Just found this thread. My Samsung Chromebook Plus exhibited the same inability to turn on, only flashing the LED white / green / blue / repeating. Had to contact Samsung support, sent them the Chromebook, and they returned it fixed.
I tried this on a Hisense Chromebook, the screen flashed a few times, and then the cycle went to amber (long) red (Flash) nothing & repeat. hoping it works but doubtful.
How long before the light turns solid red. I held Esc, Refresh, and Power. The blinking stopped after about 30 seconds but then no light ever came back on. I held it for 2-3 mins.