L90 bootloop - no emergency mode, no download mode, pc doesn't recognize
I have the same device and experienced the same behavior and it turned out to be my SD card. After I removed it my phone worked fine. I never did find out what the problem with the SD card was. I inserted it into an adapter and put it in my chromebook to see if I could run some diagnostics tool on it but it even caused my chromebook to reboot!
Hope this helps.