Just wanted to say that I am having SAME Problem, tried lots of fixes with adb and powered off cable and USB to Ethernet but it gives me no chance to allow debugging. I am going to click on above link for Fire TV Customer Support.
I had the same problem with my Fire TV 4K (The square one with the attached hdmi cable), but only if I had a USB hub connected to it. My solution was using a higher powered USB power supply for the hub. The Fire TV worked fine with a 1 Amp PSU, but went into the loop once I put the hub in the mix. Replacing the USB power supply with a 2 Amp unit solved my issue.
Hello, I had the same problem. I did not have my fire stick 4k connected to my laptop adb before I installed Google play so I could not uninstall play store and play services using adb. I came across this link and followed exactly what mentioned, It let me boot in to safe mode then I uninstalled play store and play services then did a normal boot. It works well now. (This url is non-English so allow google translate to English) I got y-otg cable from Amazon, I Kept holding ctrl+alt+menu+printscreen keys while another person assisted to plug in the fire stick power adapter. I kept hitting the "i" key. It started the regular white screen with orange amazon logo after few moments darkscreen+safemode in left bottom appeared then I got my screen. clicked "your applications" and uninstalled both culprits then power off and power on. (Both blue tooth and usb key board supports to invoke the safe mode)
This worked for me - Thank God. Take note that you have to quickly try to delete the files like every second for about 15 seconds and you'll catch the period in the machine's booting/re-booting that will allow you to properly delete them.
This worked for me as well. Do note that you have to quickly redo the adb command until it takes (it talks about this in the post, but I missed it the first time). It took me about 10 retries (up arrow, return).
I forgot I had been screwing around with Google Play Services the week before and could not get my 4K stick to get out of a bootloop. I'm a dev, so I already had adb installed. I had to find the right moment when adb server was running to get the commands to take. I've since done a factory reset and installed my apps. No more experimenting...
The link to the German site works perfectly. I previously did not authorize via USB so it didn't work. However I did via ADB wirelessly and once in safe mode quick went back into ADB and was able to Uninstalle the rogue apps. I used an android app apps2fire it's way easier than using it any other way!
Below is directly from the German site. The trick that no other post or site gave was the key combinations after you get the OTG Y cable. The keys are as follows : left-ctrl + left-at +right-menu [(between right alt & ctrl key) - - - this was the key!)] + print screen all at the same time and then pulse the "i" key. It went to safe mode immediately
Point 1: Bootloop prevention
Before you install the Google services or apps, you should enable ADB in the Fire TV settings. Then connect the stick with the USB cable (from the power adapter) to the laptop / PC. Here then appears an authorization message, which must be confirmed. Of course, also putting the hook on "always trust this PC ". If the laptop / PC does not recognize the FireTV Stick, then the necessary drivers have to be installed: Package 1 , Package 2 (Instructions ) and Package 3 (VCOM Preloader).
If it actually comes to the bootloop, then you only have to hang the Fire TV stick again on the same laptop / PC and can deinstall the corresponding app via adb.
adb kill-server adb start-server adb devices to start the service
adb shell pm list packages -f to find the app
adb uninstall com.google.android.gms to uninstall google play services
If you had this adb authorization not made in advance and would come in a bootloop, then you would indeed with the command " adb devices " find the Fire TV Stick, but could not run any more adb commands, just because there is no authorization with this laptop / PC and this because of the bootloop can not be done anymore.
Point 2: Emergency Rescue using Y-OTG cable and keyboard
If you have not performed the bootloop prevention or the laptop / PC is just not available anymore, then there is the possibility to get into the safe mode via Y-OTG cable and keyboard. There you can reset the Fire TV Stick to the factory settings.
To do this, the keyboard is connected to the Y-OTG cable. Then connect the power supply and press CTRL + ALT + I + Menu button + Print . Personally, I kept all the buttons (except for the i) pressed and pressed the i as quickly as possible in succession.This allowed me to easily enter the Safe Mode.