'93 volvo 850 glt always has dead battery, why?

Removing the Bulb did not stop the battery drain. You must find a way to repair or disconnect the drivers door switch to stop the "dinger" or chime.
The tool you used to remove the Brake calipers is Not called a Star tip, it is called a Male Torque Drive socket. Replacing the Alternator should be pretty straight forward. Disconnect the battery, remove the belt, disconnect the wires and then remove the bolts holding it on.
Reverse the procedure for installing it.

Removing the Bulb did not stop the battery drain. You must find a way to repair or disconnect the drivers door switch to stop the "dinger" or chime.
The tool you used to remove the Brake calipers is Not called a Star tip, it is called a Male Torque Drive socket. Replacing the Alternator should be pretty straight forward. Disconnect the battery, remove the belt, disconnect the wires and then remove the bolts holding it on.
Reverse the procedure for installing it.

First of all, was the battery dead, or do you have shorted turns in the field coils of your starter motor drawing heavy current?

Re-charge the battery overnight. When you think it is fully charged, disconnect the charger connectors and leave it to stand as long, or longer than you did before. DO NOT put the battery back in the car and connect it. You need to find out if there is a leakage due to something connected that is drawing current and by connecting it to the car, the battery might be drained again.

After the battery has stood for about 24 hours, if you have a voltemeter, check the voltage. If the voltage still holds up at.around 13 volts, put it in the car and immediately see if it starts. If it does, it would appear that there are no leaky cells, but if it is dead again, say goodbye to the battery, because the cells have had it.

If the car starts ok, turn it off and leave the battery in the car connected for as long as you did before and when you go to start it the next time and it is dead, it would appear that there is something draining the battery.

To find this out, you need a multimeter with a 10 amp range to put in series with the positive side of the battery, positive side of the meter to the positive post on the battery and the negative lead of the meter to the positive cable. You could use the negative side of the battery also, if you wanted, but reverse the connections of the meter first.

If you get a reading on the meter, the chances are that it is this leak draining your battery. If this is the case, look at the ignition light with the ignition off and in darkness, if possible. If the ignition light appears to be on, though very dim, it is a good indication that the regulator in the alternator has gone short circuit or the windings in the field coils in the alternator have shorted turns. If this is the case, you will find it will be easier to change the alternator rather than change the regulator, in case it is the field coils that are the problem.

If it appears as though there is no problem with the charging system and there is still a leak, you will need to disconnect as many things as you can, one at a time, until the leak stops and then follow that part of the circuit,

Hopefully, you may not have to go that far and find the problem before it gets to that stage.

Although the battery may appear to be new, don't.reply on the fact that it is. It could have been standing in the shop for ages without attention before you came along and bought it.

Let's hope this solves your problem.

First of all, was the battery dead, or do you have shorted turns in the field coils of your starter motor drawing heavy current?

Re-charge the battery overnight. When you think it is fully charged, disconnect the charger connectors and leave it to stand as long, or longer than you did before. DO NOT put the battery back in the car and connect it. You need to find out if there is a leakage due to something connected that is drawing current and by connecting it to the car, the battery might be drained again.

After the battery has stood for about 24 hours, if you have a voltemeter, check the voltage. If the voltage still holds up at.around 13 volts, put it in the car and immediately see if it starts. If it does, it would appear that there are no leaky cells, but if it is dead again, say goodbye to the battery, because the cells have had it.

If the car starts ok, turn it off and leave the battery in the car connected for as long as you did before and when you go to start it the next time and it is dead, it would appear that there is something draining the battery.

To find this out, you need a multimeter with a 10 amp range to put in series with the positive side of the battery, positive side of the meter to the positive post on the battery and the negative lead of the meter to the positive cable. You could use the negative side of the battery also, if you wanted, but reverse the connections of the meter first.

If you get a reading on the meter, the chances are that it is this leak draining your battery. If this is the case, look at the ignition light with the ignition off and in darkness, if possible. If the ignition light appears to be on, though very dim, it is a good indication that the regulator in the alternator has gone short circuit or the windings in the field coils in the alternator have shorted turns. If this is the case, you will find it will be easier to change the alternator rather than change the regulator, in case it is the field coils that are the problem.

If it appears as though there is no problem with the charging system and there is still a leak, you will need to disconnect as many things as you can, one at a time, until the leak stops and then follow that part of the circuit,

Hopefully, you may not have to go that far and find the problem before it gets to that stage.

Although the battery may appear to be new, don't.reply on the fact that it is. It could have been standing in the shop for ages without attention before you came along and bought it.

Let's hope this solves your problem.