Battery Parasitic draw test?

Yes, if current is flowing there will be voltage drop. Thats how Ohms Law works, if you know the voltage and resistance of a component you can find the current. And the other way as well. But you have to make sure that the vehicle is set up for a parasitic draw test. You don't want to chase a current draw that is happening because of a door or trunk switch that is not properly closed. Are you finding more than one fuse with voltage drop on it?

That is just an example from the voltage drop chart, I'm not saying there is 13-amps, I'm saying that is the amperage for that amount of voltage drop that would be across that size fuse. Just an example of how to read the chart.

The 2nd set of charts is better since it shows lower voltage drop readings that you will end up encountering. The first chart does not look good like that. It's just that the resistance across a fuse is so low that it will be a few decimal points back from zero, but even that little amount will reveal current flow and that's why it's a good test, you don't have to disturb any circuits to check their current flow. In some cases, if you move a wiring harness around you can accidentally move a wire and fix the issue, that happens a lot with shorts to ground. And then you can never find the issue again. So, these non-evasive tests are the ones you want to stick to. The amp clamp will help a lot too. When used with an oscilloscope you can check for shorted ignition coils or solenoids by just clamping on the feed wire and looking at the waveform to see if it's irregular, but that's a whole other learning curve.
With the amount of current you're losing, hopefully it won't be too difficult to find.
Did you figure anything out about that Hood switch yet? It's definitely part of the security system.

Now, the hood switch is an input. It's not causing the draw on the battery itself. The security system is seeing that the hood is open, hence the message you're getting on the cluster. Whatever module is responsible for the security system is going to stay awake on the network until it sees all the required inputs in their required states (such as doors closed and locked, trunk switch closed, hood switch closed, etc, ) then each system in the vehicle will start to power down, and eventually go to sleep. The CAN bus network's activity will stop. But that can't happen until the vehicle can be properly locked, and after an hour or so the security module will time out and shut down as well. This is where the larger current that draws on the battery will go down to a few milliamps. You need to figure out why the Hood switch is displaying that message to begin with.

Well, you need to see how much current flow is there after its locked up, you can keep a battery maintainer on it to keep the battery up to at least 12.6v. Wait an hour and check the draw on the battery. You should see the current flow keeps decreasing to below 50ma. If after a couple hours you still have a few amp draw, then start checking fuses. Thats going to get you to the circuits on that fuse that could potentially be the draw. Once you get to that point and have some direction, you'll need to start isolating those circuits. This is why parasitic draws on modern vehicles are so difficult. Mercedes, BWM, and other high-end vehicles are even more difficult.
Has this vehicle set any codes or had any codes when you first got it?

If you end up with something like a 5amp draw or some other crazy high number like that, these are the 4 CAN bus connectors and all the modules throughout the vehicle, you can try plugging modules and see if the draw drops down, Starting with the radio if it has an Amp. You might get lucky if the draw is really high, which sounds like it is. The OEM diagrams are really difficult to read for this vehicle, we will end up on this vehicle for a year if we go by those. But try the amp clamp out when you get it. See what different current readings you get when you open a door, or turn the Radio on, just to get an idea of the different readings. You can see there are so many modules.

It's better to use a battery maintainer that can control the amperage and you can set a certain voltage level. A battery maintainer will also have a read out of how many amps the battery is pulling. Trickle charger are really only to maintain a battery over long periods of time, not hooked up to the vehicle.

Topdon makes a really good maintainer, you can set the voltage and it has a nice display that will actually show how many amps the vehicle is pulling.
Here's the HVAC fuses, if it has rear HVAC, there is a 40amp fuse for one of its "hot at all times" circuits. Pull those and see if the battery drops off. You could probably check the battery every few hours and see a difference. Even looking at the HVAC there are so many modules just for that system.

Yeah, quality tools cost money, but if you're going to need it a lot, you need something that's not going to cook batteries. But shop around, you want a maintainer though when doing diagnostics, low battery voltage will cause issues that may not really be an issue. And it's extremely important to maintain battery voltage when programming.