If you have a non-working board, use a multimeter in continuity mode:
Often found on the early pages, this section details the battery charger IC and how it switches between AC adapter and battery power. apw70 lac391p schematic portable
What is the laptop showing (e.g., completely dead, blinking light, fan spins but no display)? If you have a non-working board, use a
: Holds the Intel Management Engine (ME) region and initializes the CPU and RAM. If you have a non-working board
Ragged waveforms or erratic frequencies indicate a failing IC, degraded bootstrap capacitor, or unstable feedback path. Conclusion and Repair Tips
: Broadwell-U (Intel 5th Generation Core i3/i5/i7) onboard CPUs.