I think Apple lied to me! water damage ********?!?!

Ok so about a year ago I supposedly had water damage. upon being told I could see the slight possibility, as I had dropped a mug on it containing a wet tea bag (yes i drink tea with the teabag in it! it is the future) I then went to turn it on, just to test it. The teabag landed on the actual apple logo on the top of the closed laptop, so I thought if i was damaged it would have been from the shock of the mug. I then proceeded to turn it on thinking water damage was unlikely. All it did was make a slight hum and the little light turn on. I then took it to the apple store to have it checked, the following day. They told me I had water damage to the motherboard. They gave an estimate of about £400 to fix it! I couldn't afford this at the time so left it in a cupboard. I tried it again every month or so but now a year later I turn it on and it works perfectly. I get to the actual desktop for about 10mins then it just restarted. Now it keeps restarting not actually getting to the desktop. Ive only let it restart a few times so it may be able to get to the desktop every now and again, but i dont want to mess it about.
My battery has also died and I must start it using the power adapter. No lights on the back and the adapter light always shows green, no orange to indicate recharging.
Now I didnt think mac laptops had nanotechnology to repair themselves, especially from water damage. I think this may be a power issue, that the laptop looses power suddenly and just restart. Any Ideas what could be causing my macbook to do this? thankyou

The logic board is inside the base of the machine. It sounds like the liquid was applied to the lid, which would have never impacted the logic board, unless it was a good amount of liquid and somehow worked its way into the base.

If I had to venture a guess, I'd say that the impact of the mug probably dislodged something and that's why you're seeing the instability. I would reseat the memory and continue to test.