Taking the crank arms off takes a little preparation, a cover must be removed before you can fit the crank puller on. But after that it pops out like any other bike's crank.

The next piece of the power conveyance puzzle is the bottom bracket.

Again we need a standard bike tool—the cartridge bottom bracket tool—to loosen this piece of hardware.

These tools may sound unusual, but they are very common for bike repair and maintenance. Good choice to stay standard, Xiaomi!