Xiaomi Redmi Series

In general these are some things that usually can be detected by only USB charging detector and affecting most of Redmi line of phones.

Common Problem

Phone only shows MI logo and keeps restarting	Most definitely just battery issue. If it asks for 1A or more from the charger and still displaying battery charging animation, it is most likely that your phone just need a new battery. I don't really advice you to do this, but if you think your battery is okay, maybe because you just buy the phone for a week or month, you can check the fuse in the BMS by opening the battery top plastic,and if it's blown, you can just solder a new jumper wire to replace the fuse, or if you have another Xiaomi battery (for the BMS), you can replace the fuse with it. If you want to replace the battery, PLEASE DO NOT BUY Xiaomi branded battery. They are fake battery with really bad BMS. Buy branded battery that sells for medium to high price, they are worth your money. If the problem still exists, you may have to replace the eMMC, unlike iPhone you generally don't need any programmer tools. There would be flashable file you can use to replace the partition and modem in each model of the phone (on progress).
Phone asking for half an Amp and won't turn on	It's most likely that you have short circuit in power line. Especially models with micro USB, constant 0.5A is short sircuit ampere. First thing you want to do is connecting the phone to computer. If your computer still detects the phone as a phone (in Snapdragon variants as 9008e Qualcomm Device) you can move to the next step, if it does not, you need to replace the CPU (it's usually as expensive as whole board and I think you'd be better just buy used working board). The second thing you want to do is checking every capacitor near the Power IC and Charging IC. If they are shorted or most of them are shorted, you will have to inject 2.8v-4.2v to them (there will be a guide to make crude short circuit detector from used tablet battery if you dont have power supply) with maximum 2A. Use 99% IPA, paint thinner, or Thermal camera to detect hot part of your board and remove them. Unless they are ICs (modem, Power, IC, e.t.c), it is okay to remove the component without replacing them especially capacitors, they are usually just 0.1nF to 10nF anyway.
Phone asking for 0.00A and wont turn on	eMMC problem. Unfortunately, eMMC module on android are as interchangeable as RAM on your PC. As long as the BGA is the same, you can salvage eMMC from another phone with same BGA footprint even from different brand and different RAM/HDD configuration. And while at it, you might want to replace the eMMC with one with higher storage and RAM capacity :)
Phone is asking 1 or more Amps but wont turn on	Well that must be either your display or backlight circuitry. Usually it's just fuse problem. Or broken line. Replacing the fuse usually is good enough because the backlight is not consuming that much power anyway. Unlike Macbook, which Apple was stupid enough to put 25v backlight rail next to data rail.

Individual Redmi Models

• Redmi 1
• Redmi Note 1
• Redmi 2
• Redmi Note 2
• Redmi 3/3s/3 Pro
• Redmi Pro
• Redmi Note 3/3 Pro
• Redmi 4 a/x
• Redmi 4 Prime
• Redmi Note 4/4x
• Redmi s2
• Redmi 5 /a
• Redmi Note 5a
• Redmi Note 5/5 Prime
• Redmi 6 /a
• Redmi Note 6
• Redmi 7
• Redmi Note 7
• Redmi 8
• Redmi Note 8