Replaced screen; ALS and distorted speaker

After cracking the original glass front on my iPhone 5, I replaced it using the "iPhone 5 Display Assembly with Home Button and Front Camera." Almost everything works fine, but I am having two problems that I haven't found a solution for.

(1) Ambient light sensor (for automatically adjusting brightness) seems to be not working. Manual brightness control works fine, and the automatically adjust setting is on, but it doesn't adjust. I've tried resetting the brightness calibration as documented elsewhere, but it doesn't appear to have any impact.

(2) The earphone speaker is somewhat distorted -- tinny and loud sounding, sounds like people are underwater; hard to hear clearly.

My guess is that I have the display seated somewhat incorrectly, but it's unclear what I would adjust. Any suggestions?