Hello fams at ifixt! I have an iPhone 6s that shows the itunes logo and gets the error -1. How can ifixit.

Backlight problem. Faulty screen and/or they damaged your motherboard lcd connector.

If you need to type your password, then I don't think it's a "memory" problem, it probably only needs a new LCD.

You delete new emails, old emails get downloaded I dont recommened the Mail app, just use your browser for emails.

Well unfortunantley you need an IC repair which costs 50$ min., its not worth it for an iphone 4s, sorry. Its time for a new phone.

I had this problem too on my iPhone 5s. I first replaced my screen (touch id was working after replacement) I updated my phone from ios 9.3.2 to ios 10.0 and then touch id stopped working What I did was downgrade it to ios 9.3.5 while it was still availible and touch id came back. I updated it recently to ios 10 and guess what? Touch id can not be activated on this iphone. Sucks :/ I guess they added new security on ios 10. Your best option unfortunantley is paying apple the 80$-90$ for a new touch id.