I recently had to replace the CMOS battery for an Emachines M5414 for a relative. The battery is in a rather hard to reach area, but instructions given at Emachines M53XX disassembly instructions give a detailed breakdown of how to disassemble the machine. The M53XX has a slightly different layout than the M5414, but the instructions are similar enough that I was able to follow them 90% of the way. Two things of note though – when removing the hotkeys panel, a spudger comes in quite handy in unlatching the panel. Credit cards cut into thin strips make great spudgers. In addition, be very careful when removing the trackpad cable from the motherboard, the latches are very delicate and hard to reach. A slight push into the side is all that is needed to lift the plastic piece up (don’t try to completely remove it) at which point, the cable should come up easily.

The CMOS battery used in M5414 is indeed a Maxell CR1220 battery, and it’s a simple replacement once the entire top assembly of the laptop is removed.