hello, you should carefully check around the battery connector and the connector itself with a magnification glass. I guess you damaged some little components when you removed the battery. If some component is missing or connector is damaged, check with microsoldering shop.

Vérifier que la nappe de l’écran est bien inséré sur la carte mère et que la nappe du face ID est bien enfichée aussi. Si tout est bien branché, il peut s agir d un problème d écran: j ai déjà eu plusieurs fois le cas (écran chinois, je ne connais pas ceux de ifixit)

Verifier le status du téléphone. https://www.att.com/deviceunlock/ Si il y a un problème de payement alors c est impossible à débloquer. Sinon cela se fait gratuitement sur le site de att

Bonjour avez vous essayé les modes de demmarage alternatifs ou au moins de zappé la Pram (alt cmd P R de memoire). https://support.apple.com/fr-fr/HT201255 apres eventuellement essayer de debrancher et rebrancher la batterie (necessite un outil specifique et l ouverture du capot inferieur

You may have damaged the main board connector .

Hello You have probably a dead battery or a defective charger function (charger port or main board). Try to change the battery (economically reasonable) .

Hello 1/ No the haptic engine is not necessary to turn on the phon. 2/ Do you tried to boot your phone with a lightning cable ? Are you sure that your batteries (old and new) are charged ? Replacement battery is sometime a lottery and a brand that worked correctly one day can be deffective in another batch. Find a good provider rather than a good brand (I saw fake Apple Battery : the brand is good… but it was a junk product) Of course you can damage your mother by many different way but it would be surprising that you manage to do it if you were a bit cautious during battery disassembling . I have notice that sometime when you disconnect the battery and reconnect it, the power button is not efficient and you need to boot with the lightning cable.

Hello, base on my personal experience on iPhone, this is typical of a dead battery (the battery is not able to accept a charge cycle ) or a trouble with the charger fonction. Since it is an ipad 1, a dead battery would not be surprising.

hello it seems your power button create multiple pulses rather than a correct on contact. The part by-itself is not expensive (flash flex ) and the repair is not difficult if you are used to repair iPhones. But you will need to dismount the display, the mother board and the rear camera. If you never did this, then be very cautious or go to a repair shop

Hello if you are confident with the battery you purchased (good reputation shop) then you may have a trouble with you phone. First i would try with another battery (i had the same trouble with new but defective battery. i will also check if battery % is decreasing /increasing normally. You may have damaged the gauge filter and the remaining information is corrupted.