Battery Popup at 25% english with system in spanish. Possible malware?
Pretty sure its just a malfunctioning battery optimization tool. About half of the time i got this it had a dismiss option but other times i couldn't do anything with my phone until I plugged it in. Try changing the following settings:

Settings > battery > advanced settings and turn off the app power monitor.

I haven't seen the pop-up since yesterday morning when I did changed them.