Samsung A40 stopped working after drop

It was charged. I opened it, disconnected and reconnected the battery (it shows 4.1V on my meter). Turning it on I just get the vibration and a single green line flash at the top of the screen. Then nothing more unless I repeat the battery disconnection. I’d just like to recover my whatsapp data. I can solder, can I try and repair something? Can I put my motherboard in another A40? Would a new LCD be enough? Thank you for any advice!