Booting Issues and Screen Failure on HP 242 G2 Notebook

[pseudoflare]

I own an HP 242 G2 notebook that is approximately 10 years old. The battery died completely, so I removed it and have been running the laptop solely on AC power with the charger for nearly two years. Over time, the original charger deteriorated, and about a year ago, the laptop began failing to boot on the first attempt. Initially, it took 2–3 tries to start, but the issue has progressively worsened. Currently, I spend 15–20 minutes repeatedly powering it on before it successfully boots. Somewhat like trying to start an old car engine, if you will.

When I press the power button, the fans briefly spin before the device shuts down abruptly. To retry, I unplug the charger, reconnect it, and repeat the process until it eventually starts. I noticed the laptop boots faster when the charger brick is warm, so I began heating it in sunlight for 15–20 minutes beforehand. This occasionally allowed a successful boot on the first try.

However, starting yesterday, even after preheating the charger, the laptop now exhibits a new problem: pressing power button immediately after plugging the charger pin does nothing, have to wait about 4-5 seconds and then press power button and upon booting, the screen blinks repeatedly in about 10-15 seconds (it can boot and reach the desktop), dimming with each cycle until it goes completely black. I replaced the old charger with a new one, but the issue persists. I’ve also disconnected all peripherals and attempted booting without any storage drives installed, ruling out OS-related causes (tested across multiple operating systems).

Could this be a motherboard, capacitor, or power circuit failure? Any guidance on troubleshooting or potential repairs would be greatly appreciated.