T40 Wouldn't power on after using the wrong Power Adapter

[cafe69]

I used the wrong Power Adapter on my T40 2373 Thinkpad model laptop by mistake which killed my battery. I purchased a new 6 cell battery and still it would not charge. When using the laptop with the battery and the correct power adapter the battery still will not charge and I noticed a high pitch humming noise coming from under the laptop close by the battery cell towards the left side when flip over. After 15-20 minutes the screen started flickering and I lost total power. IBM Support will not assist due to my mistake of using the wrong power adapter. A friend told me that I propably had fried the internal charging circuitry or possible the motherboard. Again, IBM charges an arm and a leg to even check the laptop since it's out of warranty and the local dealer said to replace the motherboard. My Question? Is there an internal power circuitry on them that can be replace or did I indeed damage the motherboard to the point that I need to replace it? What can I do, if anything? Thank you in advance for any assistance you can provide.