Turn the chair upside down and examine the bottom. If the chair features a fabric piece over the bottom, pry loose the staples holding the fabric in place with a staple remover.
Slide your hand up through the chair until you find the lever that releases the footrest. Remove your hand, then place a U-bracket over the lever. The bracket should sit flush with the chair frame on either side of the lever.
Screw 1-inch wood screws through each side of the bracket and into the frame. The wood screws should firmly hold the bracket against the lever. When you pull the lever from the outside, it will encounter the bracket and stop it from depressing.
Attach L-brackets at the bottom of the recliner where the footrest meets the chair's sides. Set one bracket near the bottom of the footrest and screw the bracket into the footrest. Screw the other side of the L-bracket into the chair frame directly beside the footrest. Attach two brackets on each side of the footrest, which will keep the footrest from moving. Place the brackets on the inside of the footrest and connect them to the frame inside the chair.
Flip the chair over so it sits upright and turn it so the back of the chair is facing you. Place three flat brackets where the back of the chair meets the seat. Screw 1-inch wood screws through the brackets and into the wood frame of the chair.