A1475 logic boards are quite expensive, while A1474 boards seem much more readily available. From my uneducated perspective, the major difference between the two is that the A1475 has a spot to hook up the LTE antennas, and I'm sure some circuitry to process it.
Can I slap an A1474 board in there and just not hook up the LTE antennas, and use the unit as a Wifi only Ipad? The reason the board is bad in the first place is the power management chip is bad (confirmed by replacing the battery and still not being able to charge).