Use the following trick to farm unlimited money and lock picks in the chapter entitled 'Return to the Hall of Heroes'. Farming lock picks (30 should be sufficient) will come in handy when going for all of the collectibles as some are behind locked doors. Farming money will come in useful in 1999 mode as it can be used to upgrade weapons and vigors as well as pay for your deaths. The money farming trick only works with the shown machine, other machines can only be possessed once. You get 40 silver eagles each time you posses the machine so it is a time consuming process.
When you have hacked a robot it will begin firing at your enemies. If the robot gets hit however it will begin to lose health, catch on fire, and eventually explode. To prevent this from happening deactivate the robot by pressing A while pointing at it and then reactivate it a few seconds later. Doing this will make the robot have full health again.