PROSTHETIC LIMBS

The most noticeable of his cybernetics include his prosthetic limbs; his left arm and both legs grant him superhuman strength and speed.
His legs are built to aide in jumping and falling. They are built for sustained stealth missions, particularly light boot-like legs that are often silent even when he's running. The shock-resistant heels allow him to fall from extreme heights and, more importantly, stick the landing; though they can break from such heights.
His hand is padded for optimal weapon-gripping, allowing him to easily use his cybernetic arm to hold a weapon for up to days if he must. The fingers are clawed. Notably, this arm also contains a small screen, which is connected to his ship's console, allowing him to call it and make calls to H.I.V.E remotely; as well as various other functions, such as stealth cloaking.

SECOND HEART

Connected to his neck and spine is a pink diamond-like shape, made out of an incredibly sturdy material. This diamond serves as a second heart, pumping blood (and hormones, if needed) through the tubes that are wrapped around his neck and back into his circulatory system. Were his actual organic heart to stop, this second heart would allow him to continue functioning. If also broken - and disconnected from his system, most importantly - then he would be considered clinically dead.
Unbeknownst to Nero and the rest of H.I.V.E, Silo has implemented multiple failsafes into this heart, to ensure that Nero cannot be remotely deactivated, killed or controlled.

EXOSUIT AND NERVES

The various external and internal wires in Nero's body are capable of connecting to his equipment. His spine is rigged to clip and connect to his exosuit, which snaps magnetically onto his skin, and is incredibly difficult to break. His exosuit is connected to his nervous system, and even if he were to be clinically dead - both his organic and cybernetic heart destroyed - his exosuit would allow him to continue fighting, ensuring that Nero can only be killed if every part of him is destroyed.

Many of his nerves connect to external apparatus, such as the horn on his head, which connects to his cybernetic eye. This horn and eye both allow him to see a HUD over his actual vision, and with his exosuit on, he can scan and track his own vitals as well as the vitals of nearby individuals.
His exosuit being connected to his nerves also serves as a pain inhibitor; and he will only feel pain when not wearing his exosuit. It, also, connects to other external gear, such as his oni mask, with contains a rebreather and visor for dangerous planets.