Should I disconnect the battery?

I have a '98 CL with a failed CD player. The radio and cassette deck still work fine. I have a replacement radio unit from Ebay which I would like to
install but I am uncertain about whether or not to disconnect the battery before proceeding. I'm not sure what the risks and consequences are and I would appreciate some informed advice.
In order to gain access to the radio I have to disconnect several electrical dash units such as the clock, seat heater buttons, etc. plus of course ultimately the radio itself. Is it safe to do so while the battery is still online? If something goes wrong does it just mean a fuse will blow or is there some risk of frying the accessory itself?
Alternatively, if I play safe and disconnect the battery then I know I will need a radio code to re-enable any radio, which should not be a problem so long as the codes I was provided are correct. I am also told it will reset the ECM, which also should theoretically not be a problem as there are currently no errors outstanding and there is no smog check is due for many months. I am not clear tho whether I would also lose my keyless entry codes and my 'garage door' codes or anything else. Does anyone know? Is there anything else to be considered before disconnecting the battery?
I'd like to have a working CD player again but not if it means risking damage to some other part(s) of the car or turning a small problem into a big one.
TIA for any helpful advice.....
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Sandy wrote:

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Ummmmmmm, Didn't you already disconnect the battery before, when you were trying to RESET the (presumed dead) CD player ?? Before you start ripping stuff apart maybe a simple 'reboot' of your existing hardware will solve the problem.
If the stereo says Anti-Theft and has a blinking LED, yes, you will need to reload the CODE after reconnecting the battery. The ECU shouldn't be a problem, and your key codes are safe, I think. The garage door stuff only takes a few minutes if it goes bye-bye.
Just try to hook the battery up 'clean', with no SPITZENSPARKEN. If you do it wrong, disconnect 30 seconds and try again.
If there's labels jammed in the CD, just change it out.
'Curly'
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