Putting this out there for search engines, since someone will probably need it some day.
Symptom: Dell Chromebook 11 inch 3380 would not turn on, despite being on charger all night. Same effect with different chargers, ruling that out as a cause. As soon as power was connected, the power light blinked at around once per second, with a very soft click (which turned out the be the fan turning on for a short blip).
I opened the back case and removed the battery connection. With power applied, the laptop would power cycle, but at a slower rate and with significantly longer fan spin. A USB monitor showed an initial 5V at the input, then 20V, followed by an immediate reset. A measurement directly at the battery showed only 0.3V on a 7.6V rated battery.
I connected to a 5V-only USB power source, and the power light stayed on. I tried it again with the battery connected, and observed a charging voltage on the battery, albeit very slow. A few hours later the battery was up to around 7.1V and I was able to connect the full power USB, where it started charging at full rate. Thereafter the laptop completed a charge cycle and turned on without problems.
So there’s an easy repair with no soldering required.
