Hp laserJet Pro M15 after a power outage it turns on, and only the power green light blinks

[JoFer808]

Hi, 

I have a LaserJet Pro M15w, and after an area power outage or I accidentally hit the power cable out, when I turn on the printer only the green power light blinking slowly. Usually on all the websites and on this site no one posts of just the green light blinking slowly, no other lights is blinking.  I use the HP easy smart program to see if I can do something there, but the program asks me to turn on the printer, so the program see that the printer is off, so no help there.  This happened like about 5 times already that I remember, but I can do a fix by holding the power button, the orange triangle button or error button, and the wifi button at the same time then I let go 1 button at a time I think. This time I gave up I forgot how to do it and its very frustrating, you have to do it in sequence like let go the error button then the wifi button, but its wrong sequence ever time I try. Please let me know if you need anymore information. 

[Samrit26]

Hello,

That’s a good detailed description, thanks. Let’s clarify a few things before I outline the recovery sequence because the behavior you’re describing (slowly blinking green Power LED only, no Wi-Fi or Attention LED) indicates the printer is in a firmware boot-loader or partial power state, often triggered by power interruption mid-cycle.

Before going further, can you confirm the following details:

1. When the Power LED is blinking slowly, does the printer respond in any way when you press the Wi-Fi or Cancel/Error button (e.g., any light change or noise)?

2. Are you connecting via USB or Wi-Fi normally?

3. Roughly how long has it been since you last updated the printer firmware? (HP released a few critical recovery-stability updates for the M15w around 2023–2024.)

4. Is this on Windows or macOS? The recovery tool differs slightly.

Once I know that, I’ll walk you through two options:

• a manual recovery key sequence (which is what you were attempting), and

• a firmware recovery via USB using HP Smart or HP Printer Update Utility.

Also, I’ll explain why this happens — it’s actually common when a LaserJet Pro M15w loses power while in standby with Wi-Fi active, as the onboard MCU sometimes fails to exit its low-power boot mode properly.

Can you provide those details so I can tailor the exact recovery sequence?

[Samrit26]

Hello,
Why this happens
The LaserJet Pro M15w uses a compact controller board that can become stuck in a partial boot state if it loses power during startup or sleep. In that condition, the Power LED blinks slowly, but the printer’s main firmware never fully loads. As a result, neither Wi-Fi nor USB becomes active, and HP Smart or HP Easy Start cannot detect it. This state can be cleared by forcing the printer into a firmware recovery or full reinitialization sequence.

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Manual recovery sequence
Use this exact order and timing:

1. Disconnect the USB cable (if connected) and unplug the power cord.

2. Wait about 30 seconds.

3. Press and hold all three buttons simultaneously:

   • Power

   • Cancel/Error (triangle)

   • Wi-Fi

4. While holding all three buttons, plug the power cable back in.
   Keep holding for about 10 seconds until the Power LED blinks faster or all LEDs flash once.

5. Release the buttons in this order:

   1. Cancel/Error

   2. Wi-Fi

   3. Power

6. Wait up to one minute.
   If the sequence is successful, the printer will run a self-test (you may hear a click or fan spin) and the LEDs will return to steady or normal blinking.

7. Once stable, reconnect the USB cable or let the printer rejoin the Wi-Fi network.

If the Power LED continues to blink slowly with no other signs of activity, the internal firmware likely needs to be reloaded using the HP Printer Update Utility.

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Firmware recovery (USB method)

1. On a Windows PC, go to HP’s support site and download the “HP LaserJet Pro M15-M16 Firmware Update Utility.”

2. Connect the printer directly to the computer with a USB cable (avoid hubs).

3. Run the utility as Administrator.

4. If the printer appears in the list, select it and start the firmware update.

5. Allow the process to complete fully before disconnecting power or USB.

6. Once updated, restart the printer and verify that the Power LED becomes solid and that HP Smart can detect it.

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This sequence normally clears the boot-loop condition after a power loss. If the printer fails both the manual reset and the USB firmware recovery (for example, if it never enumerates on USB even in recovery mode), then the controller board is unresponsive, and the only remaining option is depot repair (ship to HP’s repair center).