Hi,

I have an i486DX2 laptop, and it does not boot. Drive spins, but there's no backlight. There's only a continuous beep for a few seconds, then a few seconds break, and another beep, and so on. When I got it, I thought that's gonna be something easy like a RAM stick, BIOS battery, or some connection, but it has integrated RAM, the stick is only an extension, connections are also not a problem, and to my surprise, there's no BIOS battery. So does it use the main battery as a clock battery, or might it be some other problem?

I've checked the power supply open circuit voltage, and I took the laptop apart and did a visual inspection (bulging caps, corrosion), but those things were ok.

That is the same device:https://www-clous-cz.translate.goog/acrobat-l … S&_x_tr_pto=nui, but that revision does have a CMOS battery.