Question about E480 semi-dead Motherboard

[DLinks1292]

Greetings! I have a "semi-dead" E490 Motherboard with i5-8250U, what I meant by "semi-death" is:

• cannot charge if Internal battery plugged in, but using battery the laptop is normal without a hitch

• If battery removed, it can power on via USB-C but it send very low current, hence the CPU clock down and make the system unstable

• I tried with official ThinkPad 65w Type-c charger as well 3rd party one, including MacBook Pro 100W USB-C charger, nothing changes

• Already tried changing USB-C Port, nothing changed

Since is "Semi-Dead", I would like to convert it to a desktop system, since I got new motherboard and sell the whole unit, anyone know how to trick the charging system for sending 20V 3A or more? or there's any hacks I can use? like tricking the battery system using dummy battery, or anyone here kind enough to send me E490 schematics or at least which IC I need to replace? any help will be very appreciated! (And sorry for my bad English)