Infiniti G35 key fob battery

Key with remote in the head

1. The remote electronics sit in the plastic head of the key itself, so there is no separate fob to open.
2. Work a thin flat tool into the seam near the blade and twist; go round slowly if it does not open at once.
3. The coin cell is usually under or on the back of a small board. Keep the rubber button pad in place while you swap the cell.
4. Close the head, check there is no gap, and try the buttons.

A CR1620 is 16 mm across and 2.0 mm thick. It is easy to confuse with the 20 mm CR20xx sizes, which will not fit.

Separate remote fob

1. This remote is its own fob, separate from the metal key, which makes it one of the easier ones to open.
2. Find the slot along the edge and turn a coin in it. Go slowly so the clips do not snap.
3. Replace the cell, keeping the + side where it was, and check the small metal tab still touches it.
4. Reassemble and test from a short distance.

A CR2025 is 20 mm across and 2.5 mm thick. CR2032, CR2025 and CR2016 share the same width but not the same thickness, so a swap between them can leave a loose contact or a case that will not close.

Smart key (push-button start)

1. Start by freeing the hidden metal key: there is a latch or slide on the case, and the blade comes out once it moves.
2. Look inside the empty key slot for a notch. Put the tip of the metal key or a small flat screwdriver wrapped in tape there and twist gently until the shell splits.
3. Pop the old battery out with a toothpick or plastic pick, not a metal blade, and seat the new one with the + side matching the old one.
4. Snap the halves back together, slide the metal key home, and press each button, then try the start button from the driver's seat.

Infiniti Intelligent Keys normally hold a mechanical key behind a release knob; the slot behind it is where you pry.

A CR2032 is 20 mm across and 3.2 mm thick. CR2032, CR2025 and CR2016 share the same width but not the same thickness, so a swap between them can leave a loose contact or a case that will not close.