--DISCLAIMER--
This post is not an official notice from the manufacturer, nor should be considered as such I am an end-user, sharing techniques that have worked for me, personally. I invite anyone of a higher technical background to correct anything that sounds misleading or incorrect. This post should be not be construed as official technical advice.
--END DISCLAIMER--
I experienced a boot loop when downloading Birdseye Direct Download on my Garming GPSMAP 86sci. Firmware Release 8.80.
I got out of it, by turning the unit off completely (ten second power button hold down), removing the MicroSD Card from the unit, then rebooting without the card. This solved my problem.
I did have some Birdseye Direct images on my MicroSD Card, and it seemed the system--8.80--was boot looping while trying to load the card AFTER I tried to download on the unit. Not wanting any more problems, I did a full system reset, then Delete. I did this twice, just to be sure. I made sure that all data and the Birdseye Folder were removed from the Garmin\ directory on the Internal Storage of the 86sci.
I'd recommend Birdseye Imagery to Internal Storage when doing so from the unit over it's WiFi. External Cards have given me issue in the past, where using the Internal Storage for some types of data just seems to work better on these units.
If anyone else has experienced problems with this unit, please let me know, as I'm interested in obtaining solutions.
I hope this is helpful.
-Stephen