What is the ruling of Sharia on the continued deception of the manufacturer to obtain free spare parts for devices previously sold with a valid warranty, knowing that the company's new system does not require deception? And will Allah forgive past deceptions in this case?

What you have mentioned is clear deception, and it is not permissible to deceive or trick a disbeliever or to unlawfully consume their wealth. A Muslim must demonstrate the virtues of their religion through their conduct and interactions with Muslims and others, as this is a call to Islam. Mere repentance is not sufficient without returning what was wrongfully taken from the company's funds; it is obligatory to rectify this. As for devices sold with a warranty, their defects must be repaired using the company's money. It is not permissible to deceive the manufacturer if the warranty period has expired. It is not permissible to assist them in deception and fraud, for Allah Almighty says: "And cooperate in righteousness and piety, but do not cooperate in sin and aggression" (Quran 5:2). You are not required to leave your job as long as your field is free from prohibitions, but you must advise the workers and remind them of the impermissibility of deception.