I assumed this implicitly because itwasamystery mentioned finding a seller for an older cart and successfully flashing their DS afterwards. I've no idea in what other way the initial setup could be skipped. After taking out the battery the DS wants to repeat the initial setup and since the firmware is damaged on the settings part… this never loads. Ironically using Flashme before this happened would most likely have prevented the dead end. Flashme allows forced loading DS software from either Slot-1 or Slot-2 when holding (Start)+(Select) while turning on.
You're completely right. I'll probably keep Flashme installed for recovery purposes after this is resolved.
This one? (redacted so I can reply)
I do not know how complete this list is. There are so many Slot-1 carts out there. And actually finding something like the original R4 nowadays is probably not easy.
Yes, that one. Looks a bit incomplete/dated, but not finding a better resource at the moment.
I could not find any information about the DSTT without "i" – a flashcart only compatible with DS-phat|lite – which is still available.
(redacted so I can reply)
Maybe someone else has information about this? The chart in the wiki only mentions DSTTi – which as DSi compatible cart can't have autoboot/skipping.
That is a good find. I foolishly assumed all the old carts would not be for sale on nds-card. Per (this site) /threads/how-to-disable-dstt-auto-start.233525/ it seems like the DSTT does have autoboot. I'll dig into that a little more but I think you just found me the most time/cost-effective solution. I'll report back with any additional findings or confirmation of resolution once the cart gets here. Thank you for all the help!
UPDATE:
I wanted to make sure any future people visiting here know the results of this effort.
I was able to use the DSTT flashcart to autoboot and bypass the corrupted portion of the DS firmware. I then proceeded to attempt Flashme installation, which was working right up until my hand slipped during the install (when you're supposed to short a connection on the motherboard) and completely corrupted the DS. Now neither screen even turns on, and repairing it is much more effort than is worth it since I recently acquired a DS Lite.
@KleinesSinchen, thank you for all the knowledge and assistance. You were a tremendous help!
TL;DR: If you corrupted your DS or DS Lite in the manor stated by the OP, then get a DSTT flashcart and CAREFULLY install Flashme. If you mess that up, you can only perform firmware recovery by parallel port as mentioned by FAST6191 above. Good luck
