I went through this process today. One of the chairs either didn't work or was intermittent. It turns out the connector to the motor just under the footrest was not tight, and the two connectors at the controller were not tight.
The chairs were clamped to the floor, held by a single screw in each clamp, in three places (two out front and one adjacent to the dining table and no clamp in the back corner). After removing those the chair needs to be pulled upwards to detach from the centre storage console. They are attached by interlocking devices. Once that chair is out of the way the console can be pulled upwards to detach from the other chair. You may find these attachment points need to be tightened - every one of mine was loose. You need a hex wrench to tighten them.
I rolled each chair onto its side to get good access to the wiring. There is a connector at the front rail, the adapter, down stream from the adapter and then two on the control module that's attached at the inside back of the chair. I pushed each connection tightly together and then secured them with zip ties. It took a bit of zip tie trickery to ensure the two connectors on the control module were held down.
Everything works now.