Start on p. 34. Memory and storage are customer replacement items so no worries about warranty by doing upgrades. There are a total of 4 memory slots. 2 are behind the motherboard so not recommended to access those. However, the computer can take up to 4 x 16 gig or 64 gigs of RAM. It was shipped with a single 16 gig module so add another DDR4-2666 module (SO-DIMM) in the customer access slot and you have 32 gigs which is a ton of memory. The M.2 slot for SSD is also customer accessible. It takes a 2280 form factor NVME M.2 SSD. Your model shipped with a 256 gig and it can be upgraded to whatever you can find in the market. 2 TBs are common. Samsung 970 Evo is a good product.
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