What is the ruling on repairing and selling devices that contain unlawful content or are likely to be used for unlawful purposes, especially if quitting the job could lead to dismissal, and does the ruling differ if the unlawful content is deleted and replaced with religious materials?

If you are certain that the buyer will use the tools for unlawful purposes, then it is not permissible to sell or repair them for him. However, if you are not certain or do not predominantly believe so, then there is no objection to selling or repairing them. This ruling applies to both the shop owner and the worker. If the employer compels the worker to assist transgressors in their disobedience, then he must leave the work and seek permissible employment.