P71 not charging

[harrypad]

I found my laptop switched off and the plug of the charger had fallen out of the wall socket.
When I put it back it was very loose so I guess that's why it fell out.
However, after putting it back the LED next to the power connector on the laptop wasn't lit.
So I found a reliable extension wire, plugged in the charger, but still no LED.
Then I tried to switch on the laptop and saw the LED next to the power connector's input blinking orange/yellow shortly.
That didn't look good, so I switched off the laptop again.

Measuring the charger's voltage gave me 19.7 V, good enough I think, and the resistor between the pin and the zero on the 170 W (20V, 8.5A) charger's power connector gives 1.75 kOhm, which also looks alright according to thinkwiki .

So now I'm afraid there is something wrong inside.
Has anybody here experienced (and solved) the same issue before?
Hints would be welcome.

[RealBlackStuff]

The battery is probably completely discharged.
Remove the battery, then try again with only charger.
If OK, put the battery back in and leave it charging overnight.
If still not charging after that, get another battery.

[harrypad]

Thanks man, it runs without a battery.
Will now charge it for a night and will see what it says (battery status) when I start it up again.
If still low hopefully indeed only the battery. It is now 4 years old, but was still going strong...