Once you've bought your parts and tools, check out iFixit's MacBook Pro 13' Retina Display Mid 2014 repair guides for step-by-step instructions on how to make the fix. Our battery kits include all the needed tools. My intuition says (am owner of Mid-2014 13' Pro) that its a hardware thing. The MacBook Pro 13' Retina Display models require a P5 Pentalobe Screwdriver to remove the lower case to begin any internal repairs. Possibly run the diagnostics (hold D) on startup chime to see if it is a detectable hardware issue otherwise reinstall of MacOS as last resort incase its some sort of software bug. Our battery repair kits include the needed adhesive. The battery in a MacBook Pro 13' Retina Mid 2014 is adhered to the inside of the upper case. The most common repairs with the 13' Mid 2014 model MacBook Pro with Retina Display laptops are replacing a dead battery or a damaged display assembly. Internally, the Mid 2014 model features faster processors and 8 or 16 GB of RAM that cannot be upgraded after purchase. The MacBook Pro 'Core i5' 2.6 13-Inch (Mid-2014 Retina Display) features a 22 nm 'Haswell' 2.6 GHz Intel 'Core i5' processor (4278U), with dual independent processor 'cores' on a single silicon chip, a 3 MB shared level 3 cache, 8 GB of onboard 1600 MHz DDR3L SDRAM (which could be upgraded to 16 GB at the time of purchase, but cannot be upgraded later), 128 GB or 256 GB of PCIe-based flash storage, and an integrated Intel Iris 5100 graphics processor that shares memory with the system. Like the Early 2013 and Late 2013 models, this machine has no Ethernet or Firewire ports, although adapters are available. The Mid 2014 model has two USB 3.0 ports, an HDMI port, an SDXC card slot, a MagSafe 2 port, two Thunderbolt 2 ports, Bluetooth 4.0, and 802.11ac Wi-Fi. The 13.3' widescreen 2560x1600 (227 ppi) display, external ports, and Wi-Fi capabilities are unchanged. Externally, this 'Mid 2014' model looks very much like the 'Late 2013' model. On JApple introduced a new 13' MacBook Pro with Retina Display.

Mid 2014 macbook pro 13 retina screen