If your Amazon Fire TV Cube 3rd Gen is not turning on, you're not alone—this is one of the most common issues reported by users. Whether you're seeing a completely black screen, no LED indicator light, or the device powers on briefly then shuts off, this troubleshooting guide will walk you through proven solutions to get your streaming device back up and running. Follow these steps in order, as they're arranged from simplest fixes to more advanced troubleshooting methods.
Quick Power and Connection Fixes
Many instances of an Amazon Fire TV Cube 3rd Gen not turning on can be traced to power supply problems, loose cables, or outlet issues. Before assuming your device is defective, verify these fundamentals.
1
Check the Power Adapter and Outlet: Ensure you're using the original Amazon power adapter (model PS73BR) that came with your Fire TV Cube 3rd Gen. Third-party adapters often lack sufficient amperage. Test the wall outlet by plugging in another device like a lamp or phone charger. Try a different outlet in another room to rule out circuit issues.
2
Inspect the Micro-USB Power Cable: Examine the entire cable length for fraying, kinks, or damage at the connector ends. The Fire TV Cube 3rd Gen uses a proprietary power cable with a right-angle micro-USB connector—standard cables won't seat properly and can cause intermittent power. Disconnect and firmly reconnect both ends, ensuring you hear or feel a secure click.
3
Perform a Hard Power Cycle: Unplug the power adapter from the wall outlet and disconnect it from the Fire TV Cube. Wait a full 60 seconds—this allows capacitors to discharge completely. Reconnect the power cable to the Cube first, then plug into the outlet. Watch for the blue LED ring to illuminate; it should pulse briefly then turn solid.
Advanced Troubleshooting for Persistent Power Failure
If basic power checks don't resolve your Amazon Fire TV Cube 3rd Gen not turning on, the issue may involve HDMI handshake problems, overheating protection, or internal hardware failure.
4
Test HDMI Connection and Input Selection: Disconnect the HDMI cable from both the TV and Fire TV Cube. Inspect for bent pins or debris in the ports. Use a high-speed HDMI cable rated for 4K/HDR if possible. Plug directly into your TV—not through a receiver or soundbar—to eliminate intermediary device conflicts. Power on your TV first, select the correct HDMI input, then connect power to the Cube.
5
Check for Overheating and Ventilation: The Fire TV Cube 3rd Gen has thermal protection that prevents startup if internal temperatures are excessive. Ensure the top and side ventilation grilles aren't obstructed by other devices, books, or cabinet walls. The Cube requires at least 4 inches of clearance on all sides. If the device feels warm to the touch, let it cool for 30 minutes in a well-ventilated area before retrying.
6
Attempt Factory Reset via Button Combination: With the Fire TV Cube unplugged, press and hold both the Volume Down and Action buttons on top of the device simultaneously. While holding these buttons, reconnect power. Continue holding for 45-60 seconds until the LED ring cycles through colors. This recovery mode can revive a Cube stuck in a boot loop or with corrupted firmware preventing normal startup.
Warning: The factory reset button combination will erase all personal data, installed apps, and account settings from your Fire TV Cube 3rd Gen. Only use this method if you've exhausted other troubleshooting steps and are prepared to reconfigure your device from scratch. Have your Amazon account credentials and Wi-Fi password ready before proceeding.
Frequently Asked Questions
Why is the blue LED on my Fire TV Cube 3rd Gen blinking but the device won't turn on?
A pulsing blue LED typically indicates the Cube is attempting to boot but encountering a software or HDMI communication failure. Try disconnecting all HDMI devices from your TV, leaving only the Cube connected. If the LED stabilizes, an HDMI-CEC conflict with another device is likely the cause. Disable CEC (often branded as Anynet+, BRAVIA Link, or SimpLink) on your TV temporarily to isolate the issue.
Can a firmware update cause my Amazon Fire TV Cube 3rd Gen to stop turning on?
Yes, interrupted or corrupted firmware updates can prevent startup. If your Cube lost power during an update, the recovery mode reset described in Step 6 is your best option. Alternatively, Amazon occasionally pushes background updates that conflict with specific TV models—checking Amazon's Fire TV software version history and community forums can confirm if others are experiencing similar timing.
How do I know if my Fire TV Cube 3rd Gen has a hardware failure requiring replacement?
Hardware failure is likely if: no LED illuminates after trying multiple verified-working outlets and cables; you detect a burnt smell or see physical damage; the device makes unusual clicking sounds; or it powers on for 2-3 seconds consistently then dies regardless of temperature or connections. The Fire TV Cube 3rd Gen includes a one-year limited warranty—contact Amazon support with your purchase date and serial number (found on the bottom label) for exchange options.
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