HP Laptop Randomly Enters Sleep Mode: Internal Keyboard, Trackpad, and Display Stop Working

HP Notebook - 15-ac610tu
CPU: Intel Core i3-6100u
Ram: 4GB Samsung 1600mhz
System Board: 8135 31.43
iGPU: Intel HD 520
Storage: Team T-Force 256GB Sata 2.5
System BIOS: F.29

My laptop has a strange problem. While the laptop is running, it suddenly goes into sleep mode. At that point, the internal keyboard, trackpad, and power button stop working. However, if I connect an external monitor via HDMI, it works perfectly, and external keyboard and mouse also function fine. But none of the internal keyboard and trackpad, including the display, work anymore.
In this state, if I shut down the laptop, it doesn’t turn on immediately when I try to restart it. It turns on normally again if I try after 20-30 minutes later.
I opened the laptop's back panel and noticed that the ports soldered directly onto the motherboard are functioning, but all the components connected via strip cables, such as the power button, keyboard, trackpad, and a USB port on the right side, are not working.
I tried with HP PC Hardware Diagnostic Tools but didn't find any error.

Could someone please help me identify the exact issue causing this behavior?