Not booting after top case replacement?So, I'm previously certified as an ACMT for an Apple self-servicing and would appreciate only others with likewise experience...
Answer to: Can I replace SSD on it?The late 2013-Current rMBP uses a PCIe SSD, OWC is currently working on developing aftermarket upgrades for these models but they're presently unavailable. The previous gen rMPBs (2012-early 2013) use SATA SSDs.
Answer to: Magsafe shows very dim green light, no power onWhat you're probably seeing is a resistor, which by design reduces voltage. I'm willing to bet it looks like a miniaturized version of this? There are no fuse components on a logic board.
Answer to: Very dark screen (but still readable)More than likely an inverter issue. Inverters cause flickering when they're going out, but when they're completely dead and gone you have no power to the backlight. I would start troubleshooting the issue by replacing that. If the inverter isn't the issue then it would be the backlight built into the lcd panel. Inverter is definitely cheaper than a new panel