There are two different problems that both look like "the drawer will not open", and they have different causes. Work out which one you have first, because it saves a lot of time.

If you need cash out of the drawer right now, open it with the key underneath while you work through this. Nothing below depends on the drawer staying shut.

Press the Open Drawer button in Santé.

Check whether Santé shows "No cash drawer selected". If you see that message, the register is not linked to a cash drawer. Nothing else will work until it is. Go to Checkout > Cash drawers and confirm a drawer exists, then make sure the register is assigned to it.

Check the cable, and specifically which port it is in. On most setups the drawer is not connected to the computer at all. It plugs into the receipt printer with a cable that looks like a phone line. Flip the printer over and open the small panel underneath. The drawer cable belongs in the port that sits by itself, away from the power and USB cables. The common mistake is putting it in the port next to the power cord, which looks identical and does nothing. Click it firmly into the standalone port and test again.

Check whether receipts are printing. Because the drawer is triggered through the printer, a printer that has stopped working takes the drawer with it. If receipts are also failing, fix the printing first and the drawer usually comes back with it. See Receipt printer says "printed" but nothing comes out and Troubleshooting the receipt printer.

Restart the printer, then the terminal. Turn the receipt printer off, wait ten seconds, and turn it back on. Unplug the cable going into the card terminal and plug it back in. Then run a cash sale, using a one cent test item if you do not want to ring up anything real. If that does not do it, hold the power button on the card terminal and choose Restart, wait for it to come back and log in, and try one more cash sale.

Check the manual release. Every drawer has a lever or key underneath. If that is engaged or the drawer is locked, no amount of software will open it. This sounds obvious and it is worth ruling out early.

This one is more specific. The hardware is proven, so the question is what the sale is doing differently.

Confirm the sale is actually completing as cash. A sale that is left on hold, or finished on a different tender, will not trigger the drawer. Check the completed sale and confirm the tender recorded is cash.

Watch the timing. On a busy register the drawer can lag several seconds behind the sale rather than never opening. If staff are reporting it as broken, ask whether it opens late rather than not at all, because that is a different problem with a different fix.

Check whether it happens on every cash sale or only some. Intermittent behavior points at the USB or printer connection rather than a setting. Reseat the cable and try the printer on a direct port rather than a hub.

This is not a fault. By default Santé opens the drawer on cash sales only, which is what most stores want, since a card sale does not need the till.

If you do want the drawer to open on every payment type, that is a setting support can switch on for your store. Contact support and ask for the drawer to open for all payment types. Be aware of what you are asking for. It means the till opens on every card transaction too, which some owners specifically do not want for loss prevention reasons.

The opposite complaint, and it is also a setting rather than a fault. See Setting up checkout preferences and Open drawer button at checkout for which behavior is controlled where.

Two things that get confused with the drawer not opening:

Entering starting cash. This is done when you open the drawer for the shift, not through the Open Drawer button. Open the drawer from Checkout > Cash drawers and enter the opening amount there.

Counting the drawer. The Count Drawer option appears as part of the close out flow. If you cannot see it, check that your employee role has permission to close a drawer. Several drawer functions are permission gated, and a cashier account will not see the same options an owner does.

Get in touch sooner rather than later if receipts print but the drawer still will not open after everything above, if it has been happening for days across multiple restarts, or if the drawer will not open with the key either. That last one usually means the lock is physically jammed, so check first that it is not simply locked.