HP Envy 15-fh0023dx (LA-M798P) – Dead board, need help, schematics or EC startup procedure.

[Marcin_eS]

Hi everyone,

I'm reaching out for help with a non-working HP Envy 15-fh0023dx laptop.
The motherboard is LA-M798P rev.1.0, with an AMD Ryzen 7 7730U.

Problem description

• When powered on:

  • Power button LED lights up

  • Fans spin

  • Caps Lock LED blinks twice, then power LED turns off

  • A moment later, the power LED turns on, Caps Lock LED blinks 5 long and 3 short times (5L3S)

  • The fans stop, the screen stays black, no backlight

• CPU gets slightly warm, but there's no activity on the screen

 Voltage checks:

• 5V_ALW and 3.3V_ALW present

• 1.8V on SPI flash

• 1.8V / 1.1V / 0.6V on soldered LPDDR4X RAM (Samsung K4UBE3D AABMGCL)

• 1.0V  VRM CPU core rails

What has been done:

• BIOS has been reprogrammed several times (original and donor firmware)

• EC chip (ENE KB9542GF) has been reprogrammed from donor and extracted images

• A local repair shops gave up due to lack of schematics or boardview .They suspect EC firmware corruption, but this is not confirmed

     Request:

If anyone has:

• Schematics or boardview for LA-M798P rev.1.0 (even partial)

• EC/BIOS startup flow or debug sequence

• Blink code interpretation for 5 long / 3 short on Caps Lock

...I'd be extremely grateful.
Any suggestions, similar experiences or diagnostic tips are welcome – I’m just trying to bring this laptop back to life. 😞

Thanks in advance!

Best regards,
Marcin

[Garp_senchau]

@Marcin_eS, Welcome to HP Support Community,

Thank you for posting your query; I’m here to help by guiding you through steps to resolve this issue

What the 5L 3S Code Means

This blink pattern indicates that the embedded controller timed out waiting for the BIOS to respond—essentially a system board/BIOS timeout or failure

Power Drain

Power off fully.

Disconnect AC adapter.

If battery is removable, take it out; if not, skip removal.

Press and hold the power button for ~30 seconds to fully discharge residual charge.

Reconnect only the AC adapter (leave battery out), then power on and observe behavior.

Disconnect Battery + CMOS Coin Cell

Disassemble to access and disconnect the internal main battery and CMOS (RTC) coin cell.

Wait around 10 minutes, then press power button to drain any residual power.

Reconnect main battery (leave RTC battery disconnected initially), reassemble, plug in AC, and power on.

If it boots, shut down, reconnect the RTC coin cell (mind orientation), and try again.

Try BIOS Recovery

On some HP models, pressing Windows + B while powering on triggers BIOS recovery from a USB or onboard backup.

Reference: HP Notebook PCs - Recovering the BIOS (Basic Input Output System) | HP® Support

Remove All Peripherals & Bridges

Disconnect Wi‑Fi module, SSD (if applicable), any USB or HDMI devices.

Often the EC times out when BIOS can’t initialize a component—so removing non-essential parts might help.

Reference: HP Notebook PCs - Computer beeps or a light blinks during startup | HP® Support

I hope this helps.

Please feel free to reply here if you have any questions or if you need further clarification on any of the steps. 

Take care and have a good day. 

Did we resolve the issue? If yes, please consider marking this post as "Accepted Solution" and click "Yes" to give us a helpful vote - your feedback keeps us going!

Regards,

[Marcin_eS]

Hello Mr. Garp_senchau.
Your advice didn't help; I have this motherboard sitting bare on the workbench. On this platform (Barcelo R), the CPU communicates directly with the BIOS via SPI, but I don't have any communication on the APU_SPI: MOSi and MISO SPI BIOS. I don't know if this is due to a faulty CPU, RAM, or if the EC is communicating with other devices on the motherboard, and one of them isn't responding, causing the EC to stop the entire post-boot process. As I mentioned, I need a schematic and a boardview of the motherboard to connect to a logic analyzer to analyze the signals managed by the EC to determine what's faulty on the motherboard and why it's communicating with the 5L3S LED.

Best regards,
Marcin

[Garp_senchau]

Hey @Marcin_eS,

Thank you for your response

  

This needs one-on-one interaction. 

Hence, I'm sending a private message to assist you with the next action. 

  

Please check your Private message icon on the upper right corner of your HP Community profile Next, to your profile Name, you should see a little blue envelope, please click on it or simply click on this link. 

  

I hope this helps! Keep me posted. 

Take care and have a good day. 

Did we resolve the issue? If yes, please consider marking this post as "Accepted Solution" and click "Yes" to give us a helpful vote - your feedback keeps us going!

Regards,